JP2007260880A - Method of truing grinding wheel, and grinding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of accurately truing a grinding wheel, while preventing excessive truing, as well as efficient reshaping and efficient dressing, and also to provide a grinding machine for realizing this truing method. <P>SOLUTION: In this method of truing a grinding wheel, relative rotation of a truer to the grinding wheel is controlled so that a truer peripheral velocity ratio expressed by an expression (the peripheral velocity of the truer)/(the peripheral velocity of the grinding wheel) becomes a predetermined value, and truing of a first stage is performed to a trued surface at a small truer peripheral velocity ratio until an output value, outputted as a detecting signal, of an acoustic emission sensor (AE sensor), which outputs acoustic emission (AE) generated when the grinding wheel is brought in contact with the truer, reaches a threshold value (a threshold value 2), and thereafter, truing of a second stage is performed to the same trued surface at a large truer peripheral velocity ratio. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a grinding wheel truing method and a grinding machine, and more specifically, a grinding wheel truing method for truing a rotating truing target surface of a rotating grinding wheel with a rotating truer, and grinding for realizing the truing method. It is about the board.

  In the case of truing with a rotating truer (a grindstone correction tool such as a diamond dresser) on the surface of the rotating grinding wheel, the "truer peripheral speed" / (the peripheral speed of the grinding wheel) conventionally indicated In general, the truing target surface of the grinding wheel is subjected to a predetermined truing process by controlling the relative rotation of the truer with respect to the grinding wheel so that the speed ratio is always a constant value. . Here, in this document, the process of cutting the surface of the grindstone with a truer is referred to as “truing process”, and the workpiece (workpiece) is obtained by moving the grindstone wheel and the truer relative to each other and performing a predetermined truing process. A series of operations for correcting the shape of the grinding surface of the grinding wheel to which the grinding process is applied and regenerating the sharpness of the abrasive grains will be referred to as “truing”.

  By the way, in truing, truing is usually performed by setting the truer peripheral speed ratio to a value such as “0.5 to 0.9”. In addition, about the rotation direction of a truer, it is normal to make it a reverse direction with respect to the rotation direction of a grinding wheel so that a contact part with a grinding wheel may move in the same direction, and a peripheral speed ratio is The ratio between the peripheral speed of the grinding wheel that rotates relatively in this way and the peripheral speed of the truer is represented by “+ value (plus value)”.

  The truing with such a truer peripheral speed ratio can achieve so-called “sharpness” by crushing abrasive grains and regenerating sharpness by applying a destructive force by the truer to the surface portion of the grindstone. However, in such truing at the truer speed ratio, it is impossible to apply a large shearing force to the surface part of the grindstone, and the shape of the grindstone surface is corrected by removing unnecessary abrasive grains and binder. In reality, the so-called “reforming” is not necessarily performed efficiently. In particular, when the grindstone of the grinding wheel is a high-strength grindstone such as a CBN grindstone (cubic boron nitride grindstone), the reality is that the reshaping efficiency is significantly reduced. Here, by setting the Truer peripheral speed ratio to a small value, it is possible to apply a large shearing force by the Truer to the surface portion of the grindstone so that the shaping can be performed efficiently. Though conceivable, in this case, there is a problem that good sharpening cannot be realized.

  On the other hand, a truing method has been devised for appropriate truing processing in the entire truing by changing the truer peripheral speed ratio to perform reshaping and sharpening, respectively.

Japanese Patent Laid-Open No. 5-138532

  However, the following problem arises simply by changing the Trure peripheral speed ratio for an appropriate truing process.

  In the whole truing, it is assumed that the shape is reformed by executing a predetermined first stage truing process that is determined in advance, and then the sharpening is simply performed by executing a predetermined second stage truing process that is determined in advance. , Reshaping may be insufficient. Even if the surface of the grindstone that is insufficiently reshaped is sharpened, there is a possibility that the insufficient reshaping cannot be corrected depending on this sharpening.

  On the other hand, if it is attempted to complete the shaping by the first stage truing process, a sufficient amount of the grindstone must be removed from the surface of the grindstone in the first stage truing process. Excessive removal of the grindstone is forced. Here, excessive removal of the grindstone in truing not only wastes the grindstone, but also unnecessarily increases the truing time so that accurate truing without excessive removal of the grindstone can be performed. It is requested to do.

  The present invention has been made in view of the above-described actual situation, and not only can the shaping and sharpening be performed efficiently, but also the truing of the grinding wheel capable of performing accurate truing without excessively removing the grinding stone. It is an object to provide a method and a grinding machine that realizes the truing method.

The main means taken by the present invention to solve the above problems are as follows:
The relative rotation of the truer with respect to the grinding wheel is controlled so that the "truer peripheral speed ratio" indicated by "((Turuer's peripheral speed) / (Grinding wheel's peripheral speed)" becomes a predetermined value. A truing method for a grinding wheel for truing a truing target surface by a rotating truer,
The first stage of truing processing is performed on the truing target surface with a small ratio of the peripheral speed of the torquer until the output value of the acoustic emission sensor that outputs the acoustic emission generated as a detection signal when the grinding wheel contacts the truer reaches the threshold value. After that, the second truing process is performed on the same truing target surface with a large truer peripheral speed ratio.
It is.

  In the truing method having the above-described configuration, the first stage truing process with a reduced truer peripheral speed ratio can be efficiently reshaped, while the second stage truing process with a large truer peripheral speed ratio is conspicuous. Can be performed efficiently. In addition, an acoustic emission sensor (hereinafter referred to as “AE sensor”) converts acoustic emission (hereinafter referred to as “AE”) such as collision sound and destruction sound generated by contact between members into a voltage, and this voltage is used as a detection signal. By monitoring the output value of such an AE sensor and determining that the first stage of truing processing has been completed when the output value reaches the threshold value, it is confirmed that the reshaping has been completed. Can grasp. Therefore, according to the truing method having the above-described configuration, the shaping can be efficiently performed by truing processing at a small truer circumferential speed ratio, and the sharpening can be efficiently performed by truing processing at a large truer circumferential speed ratio. In addition, accurate truing can be performed in the entire truing without excessively removing the grindstone.

In the means described above,
“When the truer is in contact with the grinding wheel and the truer is moved relative to the grinding wheel over a range beyond the truing target surface of the grinding wheel, the entire truing target surface of the grinding wheel The grinding wheel truing method is characterized in that the condition that the output value of the acoustic emission sensor reaches a threshold value over a period of time is a condition for ending the truing process in the first stage "
It is good.

  When it is determined that the reshaping has been completed based on the output value of the AE sensor, it may be determined that the reshaping has been completed when the output value of the AE sensor locally reaches the threshold on the entire truing target surface. .

  However, in such an aspect, although the local truing state of the truing target surface can be grasped, the truing state of the entire truing target surface cannot be grasped. Here, the grinding surface of the grinding wheel (the surface on which the workpiece is ground) is not necessarily uniformly worn by the grinding of the workpiece, and reshaping has been completed by the local truing state of the truing target surface. If it is determined whether or not, a part of the truing target surface may be reshaped and insufficient.

  Therefore, in the above means, the truer is moved over a range exceeding the truing target surface of the grinding wheel, the truing state is monitored over the entire truing target surface, and the threshold is set over the entire truing target surface. If the reached output value is obtained, it is determined that reshaping has been completed. Thereby, it is possible to prevent a lack of reshaping in a part of the truing target surface.

  In addition, in order to move the truer over the range beyond the truing target surface, the true position where the truer does not come into contact with the grinding wheel which is the movement end position from the relief position where the truer does not come into contact with the grinding wheel which is the movement start position. Until then, it may be moved in the truing feed direction along the truing target surface. When the truing target surface is a flat surface such as a cylindrical surface, a conical surface, or a flat end surface, the truer is moved to the truing target surface of the flat surface by moving the truer along the truing target surface. If the truing target surface is an uneven surface such as a surface shape that follows the shape of the workpiece to be ground, follow the outline of the cross section of the uneven surface. Will move.

In the means described above,
“The truing process in the first stage is a negative value by rotating the truer with respect to the grinding wheel so that the grinding wheel and the truer move in the opposite direction at the contact portion between the grinding wheel and the truer. A truing method of a grinding wheel characterized by including a truing process of a peripheral speed ratio "
It is good.

  Here, in the truing method having the above-described configuration, in the entire first stage truing process, the aspect is such that the true is always relatively rotated with respect to the grinding wheel so that the truer speed ratio is a negative value, and In a part of the whole truing process in the first stage, both aspects of the aspect in which the truer is rotated relative to the grinding wheel are included so that the truer peripheral speed ratio becomes a negative value.

  When the Truer peripheral speed ratio is a negative value, the so-called “up-cut” state in which the Truer moves greatly in the reverse direction with respect to the truing target surface of the grinding wheel is not only easy to bite into the grinding wheel, but also the grinding wheel. A large shearing force is applied to the surface of the lure by the truer. Therefore, the surface portion of the truing target surface of the grinding wheel can be smoothly removed by the truer, and reshaping can be performed more efficiently.

  Note that in some aspects of the entire first stage truing process, the truer speed ratio is set to a negative value in the initial stage of the first truing process. In this way, after rough reshaping, the truer speed ratio is set to a positive value in the latter stage of the first truing process, so that the finishing reshaping is performed. Then, at the beginning of the first stage of truing processing, it is possible to efficiently perform reshaping with some rough dimensional accuracy, and to ensure a high degree of reshaping accuracy when the first stage of truing processing is completed. To preferred.

Moreover, the main means taken by the present invention to solve the above-mentioned problems are as follows:
“With a grinding wheel that is driven to rotate,
A truer that is rotationally driven and is relatively moved in the axial direction and the radial direction of the grinding wheel with respect to the grinding wheel,
An acoustic emission sensor that outputs as a detection signal an acoustic emission generated when the grinding wheel and the truer come into contact with each other;
Truing of a rotating grinding wheel by controlling the relative rotation of the truer with respect to the grinding wheel so that the ratio of the true value of the truer indicated by "(Turur's circumferential speed) / (Gear wheel's circumferential speed)" becomes a predetermined value. A control device for truing a target surface with a rotating truer, and after performing the first stage truing process on the truing target surface with a small truer peripheral speed ratio until the output value of the acoustic emission sensor reaches a threshold value, A grinding machine comprising a control device for performing a second stage truing process on the same truing target surface with a truer peripheral speed ratio "
It is.

  According to this grinding machine, since the control device configured as described above is provided, not only the reshaping and sharpening can be performed efficiently, but also the true truing without excessive removal of the grindstone can be performed. The above truing method can be realized.

  As described above, according to the present invention, both the shaping and sharpening can be efficiently performed, and the truing method for a grinding wheel capable of performing accurate truing without excessively removing the grinding wheel, and this A grinding machine that realizes the truing method can be provided.

  Next, an example of an embodiment of a grinding wheel truing method and a grinding machine according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a grinding machine 10 (specifically, a cylindrical grinding machine). The grinding machine 10 includes a bed 20 constituting a base, a grinding wheel base 30 that supports a grinding wheel S, and a work base 40 that supports a work W. Here, the grinding wheel base 30 includes a shaft head 31 that rotatably supports a grinding wheel shaft 32 that serves as a rotational shaft of the grinding wheel S, and a grinding wheel shaft rotation drive device (not shown) that rotates the grinding wheel shaft 32. The grinding wheel S is detachably mounted on the grinding wheel shaft 32 of the shaft head 31 and is driven to rotate. The work table 40 includes a main shaft 42 that supports one end of the work W, a main shaft rotation drive device (not shown) that rotates the main shaft 42, and the other end of the work W. A tailstock 43 having a center 44 that rotatably supports the end portion is provided, and the workpiece W is supported between the spindle 42 of the spindle stock 41 and the center 44 of the tailstock 43 and is ground. At times, it is driven to rotate.

  The grinding wheel base 30 is assembled on the bed 20 so as to be movable in the radial direction of the main shaft 42 (hereinafter referred to as “X-axis direction”) by an appropriate slide mechanism such as a feed screw mechanism or a linear motor mechanism. It is driven to move in the X-axis direction by an axis driving device (not shown). The work table 40 is assembled on the bed 20 so as to be movable in the axial direction of the main shaft 42 (hereinafter referred to as “Z-axis direction”) by an appropriate slide mechanism such as a feed screw mechanism or a linear motor mechanism. These are moved in the Z-axis direction by a Z-axis drive device (not shown). With this configuration, the grinding machine 10 can relatively move the grinding wheel S and the workpiece W in the Z-axis direction and the X-axis direction.

  The spindle head 41 is provided with a truer base 51 to which a truer T is detachably attached, and the grindstone shaft 32 is incorporated with an AE sensor 52 that detects contact between the grinding wheel S and the truer T. ing. Accordingly, the grinding machine 10 includes the truing device 50. In the truing device 50, the grinding wheel S and the truer T are moved in the Z-axis direction, which is also the axial direction of the grinding wheel S, and the grinding wheel. It can be moved relatively in the X-axis direction, which is also the radial direction of S.

  In this example, the grindstone of the grinding wheel S is composed of a CBN grindstone (cubic boron nitride grindstone), and is formed as a disk as a truer T so that the grindstone can be properly trued. A rotary type truer T that is rotationally driven during trueing is adopted by a truer rotation drive device (not shown) embedded with diamonds on the entire circumference of the outer peripheral surface and incorporated in the truer base. Further, the AE sensor 52 is incorporated at the tip of the grindstone shaft 32 and has a structure in which the rigidity of the mounting portion of the grinding wheel S on the grindstone shaft 32 can be easily secured. Here, the closer the AE sensor 52 is to the mounting portion of the grinding wheel S, the more accurately it is possible to detect AE that occurs when the grinding wheel S comes into contact with other members, and it becomes difficult to pick up noise. If the rigidity of the shaft 32 can be sufficiently secured, it is also preferable to incorporate it into the mounting portion of the grinding wheel S.

  By the way, this grinding machine 10 is provided with the control apparatus 60 comprised using computers, such as a CNC control apparatus. Here, the control device 60 performs automated grinding by numerical control by executing a predetermined machining program, and is automated by numerical control by executing a predetermined truing program. Truing. The control device 60 has, as functional components, an X-axis control means 61 for controlling the X-axis drive device, a Z-axis control means 62 for controlling the Z-axis drive device, and a spindle control means for controlling the spindle rotation drive device. 63, a truer control means 64 for controlling the truer rotation drive device, and a grindstone shaft control means 65 for controlling the grindstone shaft rotation drive device.

  In addition, when performing truing, the control device 60 “controls the relative rotation of the truer with respect to the grinding wheel so that the truer circumferential speed ratio becomes a predetermined value”. In addition, from the AE sensor 52, The detection signal that is output is monitored. “After the first truing process is performed on the truing target surface with a small truer peripheral speed ratio until the output value of the AE sensor reaches the threshold value, the large truer peripheral speed ratio is "A second truing process is performed on the same truing target surface", such as a grindstone shaft driving device, a truer rotation driving device, an X-axis driving device, a Z-axis driving device, etc. of the grinding machine 10 (the truing device 50). Control the drive of the equipment.

  Next, the details of truing will be described. In truing, the truing target surface of the grinding wheel S is subjected to a predetermined truing process by the truer T on the basis of the position of the truer T when the truer T starts to contact the grinding wheel S. The shape of the grinding surface of the grinding wheel S is corrected and the sharpness of the abrasive grains is reproduced. In the following, the outer surface of the grinding wheel S is set as the truing target surface, and the truing target surface is illustrated as an example. explain. Not limited to this, an appropriate grinding surface such as an end face of a grinding wheel can be used as a truing target surface. In the following description, the outer peripheral surface of the cylindrical grinding wheel S, which is a flat surface, is used as a truing target surface, but the truing target surface is not only a flat surface but also a total grinding wheel that matches the shape of the workpiece to be ground. In this case, the truing can be performed by moving the truer T in the truing direction by following the truing target surface having the concavo-convex with a predetermined cutting amount.

  FIG. 2 shows a state where the outer peripheral surface of the grinding wheel S is a truing target surface and this truing target surface is truing with a truer T. Here, in the truing of the present example, the axial direction of the grinding wheel S is set as the “truing feed direction” in which the truer T is moved during the truing process, and the axial direction of the grinding wheel S is the amount of the grinding wheel cut off during the truing process. Assuming that the “cutting direction” indicating the direction and moving the truer T once in the truing feed direction with a predetermined cutting amount is one “truing stroke”, a plurality of truing strokes (truing strokes A to B in FIG. 2) I reference) is repeated, and the surface portion of the grindstone is gradually removed along the truing target surface for each truing stroke. Further, in each truing stroke, the truer T is securely attached to the grinding wheel S from the starting end of the truing stroke, which is a relief position on one side in the truing feed direction that does not reliably contact the grinding wheel S. By moving in the truing feed direction toward the end of the truing stroke, which is the escape position on the other side of the truing feed direction that does not contact the truing feed direction, the truer T is moved over a range exceeding the truing target surface. .

  FIG. 2 shows a state of the grindstone in which the central portion of the truing target surface is greatly worn by grinding the workpiece. For convenience of explanation, the wear of the grindstone and the depth of cut for each truing stroke are exaggerated. In reality, the wear and cut amount of the grinding wheel is small.

  On the other hand, during this truing, the control device 60 monitors the detection signal output from the AE sensor 52, and FIG. 3 shows an example of the AE signal waveform output from the AE sensor 52.

  The graph of FIG. 3 shows the relationship between the AE signal waveform (voltage) output from the AE sensor 52 and time, and the AE signal waveform is in the + region and the − region on the basis of the voltage 0. In this graph, the upper limit value of the amplitude is schematically shown by a straight line so that the waveform of the amplitude is omitted.

  In this truing, first, the grinding wheel S is rotated so that the circumferential speed of the grinding wheel S always becomes a predetermined circumferential speed such as a circumferential speed (for example, 120 m / s) when the workpiece is actually ground. Control. On the other hand, with respect to the truer T, its peripheral speed is made sufficiently lower than the peripheral speed of the grinding wheel S (for example, 36 m / s), and the truer speed ratio is smaller than that in the finishing truing process described later ( For example, the rotation is controlled to be 0.3).

  Next, the truer T is positioned at the truing start position a with respect to the grinding wheel S, and a predetermined first feed speed (for example, 3000 mm) in the truing feed direction from the start position a toward the end end. / Min) to perform the first truing stroke A. At this time, if the truer T does not come into contact with the grinding wheel S, it is a so-called “idle swing”, and no contact detection signal is output from the AE sensor 52, and only noise 1 is output (part A in FIG. 3). See).

  Next, the truer T is brought closer to the cutting direction of the grinding wheel S so as to reach a predetermined first cutting amount (for example, 10 μm) from the end of the first truing stroke A, and then this closer position is started. As the end, the second truing stroke B is performed by moving the truing stroke in the truing feed direction at a predetermined first feed speed that is the same feed speed as the truing stroke A. At this time, when the truer T comes into contact with the grinding wheel S, a contact detection signal is output from the AE sensor 52 (see the portion B in FIG. 3). Here, if the output value of the AE sensor 52 does not reach a predetermined threshold value 1, a truing stroke (see truing strokes C and D) with the same amount of cutting as the truing stroke B is repeated. As a result, the degree of contact between the grinding wheel S and the truer T increases, and an output value exceeding the threshold value 1 is eventually obtained in a part of the truing target surface (see D portion in FIG. 3).

  In this way, even if it is local, the rough truing process, which is the initial stage of the first stage, is completed when the output value reaching the threshold value 1 is obtained. In the subsequent truing strokes (see truing strokes E to G), the feed speed and the cutting amount are set to a predetermined second feed speed (for example, 2000 mm / min) slower than the first feed speed, respectively, Change to a predetermined second cut amount (for example, 7.5 μm) smaller than the cut amount, repeat the truing stroke (see truing strokes E to G), and perform the medium finish truing process, which is the latter stage of the first stage. Do.

  Next, in this intermediate finish truing process, when an output value exceeding a predetermined threshold value 2 is obtained from the AE sensor 52 over the entire truing target surface (see part G in FIG. 3), at this time point Then, assuming that the shaping of the truing target surface is completed, the finishing truing process in the second stage is performed thereafter.

  In this finishing truing process, compared to the previous truing process, the peripheral speed of the truer T is increased (for example, 90 m / s), the value of the truer speed ratio is increased, and "1" is set. As a close value (for example, 0.75), the abrasive grains exposed to the truing target surface are crushed to regenerate the sharpness of the ground surface. Further, the feed rate and the cut amount are set to a predetermined third feed rate (for example, 1000 mm / min) slower than the second feed rate, and a predetermined third cut amount (for example, 5 μm) smaller than the second cut amount. To complete the reshaping with a high degree of dimensional accuracy. In this example, the finishing truing process is performed by performing two truing strokes (see truing strokes H and I) to ensure both high dimensional accuracy reshaping and good sharpness reproduction. I can do it.

  As mentioned above, although the example of the truing method of the grinding wheel and grinding machine concerning this invention was demonstrated, this invention is not restricted to this, In the range which does not deviate from the summary of this invention, an appropriate change is possible.

  For example, the grinding machine for realizing the truing method according to the present invention may be a grinding machine of another type other than the cylindrical grinding machine. In addition, the AE sensor is not limited to the one provided on the grindstone shaft, and may be provided at another part on the grinder base side, an appropriate part on the table base side such as a truer base, or an appropriate part of the bed. Good. Furthermore, the truing method according to the present invention can be realized not only by a grinder equipped with a truing device but also by an independent truing device as a device exclusively for truing.

  In the above example, two truing strokes of the truing strokes H and I are performed as the finishing truing process, but the present invention is not limited to this, and a single truing stroke may be performed. However, it is preferred to perform at least two truing strokes and more preferably at least three truing strokes. If there is a difference in the amount of grinding stone removed in the truing process just before the finishing truing process, this difference will affect the next truing process, the finishing truing process. In addition, it is difficult to realize truing that regenerates the constant sharpness of the abrasive grains.

  In the above example, the entire truing is constituted by three types of truing, such as rough truing, intermediate finishing truing, and finishing truing, but the rough truing may be omitted. In the rough truing process, rough shaping may be performed by setting the truer speed ratio to a negative value. Furthermore, the truer speed ratio in the second stage truing process configured by finishing truing process is set appropriately in the range of “0.5 to 0.9”, as in the conventional truing method, which is always constant. Thus, the abrasive grains can be crushed satisfactorily. And as a truer peripheral speed ratio in the first stage truing process constituted by rough truing process and intermediate finish truing process, a smaller value (including a negative value) than the peripheral speed ratio in the second stage truing process These may be set as appropriate.

  Here, in the present invention, since the second stage truing process is a truing process that emphasizes sharpening rather than reshaping, the Truer peripheral speed ratio during the second stage truing process is set to “0.5 or more. "Even if it is set to a large value close to" 1 ", such as" 0.7 or more ", the reshaping efficiency is not greatly reduced. Therefore, the efficiency of sharpening can be actively promoted by setting the truer speed ratio during the second stage truing process to a large value. In particular, if the truer speed ratio when sharpening is a small value such as “0.3” as described in Japanese Patent Laid-Open No. 5-138532, good sharpening can be performed on the CBN grindstone. Although there is a possibility that it cannot be performed, by setting it to a large value close to “1” such as “0.5 or more”, preferably “0.7 or more”, it is possible to make a good sharpening for the CBN grinding wheel. Can do.

  In the present invention, since a plurality of types of truing processes having different feed speeds and cutting amounts such as rough truing process, intermediate finishing truing process and finishing truing process are not essential requirements, individual truing processes in a series of truing processes are not required. In the truing process, either the feed speed or the cut amount, or both the feed speed and the cut amount may be the same.

  In addition, when the truer is positioned at the start position (position a in FIG. 2) that is not in contact with the grinding wheel and truing is started, the shape dimension of the grinding wheel S indexed by the previous truing is set. On the other hand, if the next truing start position is determined with reference to the shape of the grinding wheel ascertained by the previous truing, such as a position where a predetermined cutting amount is added, the first truing It is possible to perform truing that makes it difficult for the stroke to become an oscillating truing stroke, thereby eliminating an unnecessary truing stroke that is oscillated. In addition, by determining the starting position with reference to the dimensional shape of the grinding wheel immediately before truing, which is determined from the shape and size of the workpiece that was actually ground, the first time of truing stroke ensures that the true is attached to the grinding wheel. You may make it contact.

  On the other hand, with reference to the shape of the grinding wheel determined from the previous truing or ground workpiece, the starting position is determined so that the truer does not contact the grinding wheel with the first truing stroke. Also good. By doing so, it is possible to prevent the truing process having an excessive cutting amount from being performed in the first truing stroke.

  Further, the grinding wheel and the truer are brought relatively close to each other, the start of contact between the abrasive wheel and the truer is detected by the AE sensor, and a series of truing is performed based on the position of the truer when the contact is started. It is good. In such an aspect, it is only necessary to determine that the contact between the grinding wheel and the truer has started on the condition that the output value of the AE sensor reaches the threshold value for determining contact start. Therefore, the threshold value for determining the contact start must be set sufficiently high so that it can be clearly distinguished from the noise. Therefore, until the contact judgment between the grinding wheel and the truer is completed, the peripheral speed of the grinding wheel is preferably made slower than the subsequent series of truing processes. This is because by reducing the peripheral speed of the grinding wheel, the output value of noise can be reduced, and a highly accurate contact start position between the grinding wheel and the truer can be detected.

It is a top view which shows an example of the grinding machine which concerns on this invention. It is the schematic which shows the state which performs truing by the truing method which concerns on this invention. It is a graph of the AE signal waveform at the time of truing shown in FIG.

Explanation of symbols

S Grinding wheel T Truer W Work 10 Grinding machine 20 Bed 30 Grinding wheel base 31 Shaft head 32 Grinding wheel shaft 40 Work base 41 Spindle base 42 Spindle 43 Tailstock 44 Center 50 Truing device 51 Truer base 52 AE sensor 60 Control device

Claims (4)

Truing of a rotating grinding wheel by controlling the relative rotation of the truer with respect to the grinding wheel so that the ratio of the true value of the truer indicated by "(Turur's circumferential speed) / (Gear wheel's circumferential speed)" becomes a predetermined value. A grinding wheel truing method for truing a target surface with a rotating truer,
The first stage of truing processing is performed on the truing target surface with a small ratio of the peripheral speed of the torquer until the output value of the acoustic emission sensor that outputs the acoustic emission generated as a detection signal when the grinding wheel contacts the truer reaches the threshold value. Then, a second truing process is performed on the same truing target surface with a large truer peripheral speed ratio.   When the truer is in contact with the grinding wheel and moved relative to the grinding wheel over a range beyond the truing target surface of the grinding wheel, the entire truing target surface of the grinding wheel 2. The truing method for a grinding wheel according to claim 1, wherein the condition that the output value of the acoustic emission sensor reaches a threshold value is set as the ending condition of the truing process in the first stage.   The truing process in the first stage is performed by rotating the truer with respect to the grinding wheel so that the grinding wheel and the truer move in the opposite direction at the contact portion between the grinding wheel and the truer. The truing method for a grinding wheel according to claim 1, further comprising a truing process of a speed ratio. A grinding wheel that is driven to rotate;
A truer that is rotationally driven and is relatively moved in the axial direction and the radial direction of the grinding wheel with respect to the grinding wheel,
An acoustic emission sensor that outputs as a detection signal an acoustic emission generated when the grinding wheel and the truer come into contact with each other;
Truing of a rotating grinding wheel by controlling the relative rotation of the truer with respect to the grinding wheel so that the ratio of the true value of the truer indicated by "(Turur's circumferential speed) / (Gear wheel's circumferential speed)" becomes a predetermined value. A control device for truing a target surface with a rotating truer, and after performing the first stage truing process on the truing target surface with a small truer peripheral speed ratio until the output value of the acoustic emission sensor reaches a threshold value, A grinding machine comprising: a control device that performs a second stage of truing processing on the same truing target surface with a truer peripheral speed ratio.

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