JP4929790B2 - Truing method of grinding wheel - Google Patents

Description

  The present invention relates to a truing method for a grinding wheel, and more specifically, truing a grinding wheel for truing a truing target surface of the grinding wheel with a truer while monitoring the contact state between the grinding wheel and the truer using an acoustic emission sensor. It is about the method.

  When truing a truing target surface of a grinding wheel with a truer (a grindstone correction tool such as a diamond dresser), a predetermined truing process is performed. Conventionally, from the start of truing to the end of truing, for example, feed speed In general, the truing process is performed with constant truing conditions such as the amount of cut and the amount of cut. 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”.

JP 2005-2112019 A

  By the way, when truing is performed with the truing condition being constant, when the truing is completed on the truing target surface, the grinding surface is reshaped with a high degree of dimensional accuracy and the sharpness of the abrasive grains is regenerated. Since both must be realized, a truing condition for obtaining a high truing accuracy must be set, for example, by setting a sufficiently slow feed rate and a minute cutting amount. Here, the truing target surface of the grinding wheel may be greatly deformed due to wear during grinding, and in this case, the surface part of the grinding wheel is removed in large quantities by repeating the truing process and reshaped. However, if the truing process is repeatedly performed under the truing condition where a high truing accuracy is obtained, the efficiency of the reshaping deteriorates.

  Therefore, the inventor of the present application has conducted intensive research on how to make it possible to perform reshaping efficiently, and as a result, truing processing that emphasizes efficiency over accuracy under truing conditions with low truing accuracy. After the above, a new truing method has been devised that enables truing processing under truing conditions with high truing accuracy to ensure the desired dimensional accuracy for reshaping.

  However, in the entire truing, simply performing truing processing with different truing conditions causes the following new problems.

  Rough shaping is performed by executing a predetermined truing process determined in advance under truing conditions with low truing accuracy, and then a predetermined truing process determined in advance with truing conditions having high truing accuracy is performed. When trying to ensure the dimensional accuracy, rough shaping by the truing process performed earlier is insufficient, and this insufficient rough shaping cannot be corrected by the subsequent truing process. May occur.

  On the other hand, if the rough shaping process is to be completed by the truing process that is performed first, a sufficient amount of the grindstone must be removed from the surface portion of the truing target surface by the truing process that is performed first. In other words, the grindstone must be removed excessively. 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 circumstances, and provides a truing method for a grinding wheel that not only can perform reshaping efficiently but also can perform accurate truing without excessively removing the grinding wheel. Let it be an issue.

The main means taken by the present invention in order to solve the above problems is as a first means,
“Monitoring the output value of the acoustic emission sensor that outputs the acoustic emission generated when the grinding wheel and the truer come into contact with each other as a detection signal.
When the truer is moved relative to the grinding wheel over a range exceeding the truing target surface of the grinding wheel, the output value of the acoustic emission sensor is a part of the entire truing target surface of the grinding wheel. in reaching a threshold, after the low-precision truing machining at low truing precision truing conditions, and performing high-precision truing machining at high truing precision truing conditions for the same truing target surface The truing method of a grinding wheel "
It is.

  Here, the truing conditions are the feed speed, the amount of cutting, the ratio of the true speed of the truer (the ratio of the peripheral speed of the truer to the peripheral speed of the grinding wheel when a rotating truer is used, These are various setting items set in the truing process, such as indicated by the value of the peripheral speed of the grinding wheel). And the truing conditions with low truing accuracy are a fast feed speed, a large cutting depth, a small truer circumferential speed ratio, etc., compared with the truing conditions with high truing accuracy.

  In the truing method having the above-described configuration, reshaping can be performed efficiently by low-accuracy truing processing under truing conditions with low truing accuracy. Here, reshaping in low-precision truing processing is rough reshaping that corrects the grinding surface deformed by grinding processing to a certain shape, but after low-precision truing processing, under truing conditions with high truing accuracy By performing high-accuracy truing processing, it is possible to realize reshaping with a desired dimensional accuracy.

  In the truing method having the above-described configuration, at least one of the setting items of various truing conditions such as feed speed, cutting depth, and truer speed ratio is set by low-precision truing processing and high-precision truing processing. However, by changing a plurality of setting items, more efficient reshaping can be realized in the low-accuracy truing process.

  By the way, an acoustic emission sensor (hereinafter referred to as “AE sensor”) converts an acoustic emission (hereinafter referred to as “AE”) such as a collision sound or a destruction sound caused by contact between members into a voltage, and this voltage is used as a detection signal. Output. Therefore, if the output value of such an AE sensor is monitored and it is determined that the low precision truing process for rough shaping is completed when the output value reaches the threshold value, rough shaping is completed. Can be accurately grasped. Therefore, accurate truing can be performed in the entire truing without excessively removing the grindstone.

  The low-precision truing process is intended to rough shape the deformed ground surface with emphasis on efficiency rather than accuracy, but this low-precision truing process provides a rough shape for the entire truing target surface. Excessive repair may cause problems such as unnecessarily dropping abrasive grains that can still withstand use and unnecessarily crushing well-open pores.

  On the other hand, in the truing method configured as described above, the low-accuracy truing process is terminated on the condition that the output value of the acoustic emission sensor reaches a threshold value in a part of the entire truing target surface of the grinding wheel. It is possible to prevent excessive reshaping and to prevent the above-described problems from occurring.

  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.

Moreover, the main means taken by the present invention to solve the above-mentioned problems is as the second means ,
“Monitoring the output value of the acoustic emission sensor that outputs the acoustic emission generated when the grinding wheel and the truer come into contact with each other as a detection signal.
When the truer is moved relative to the grinding wheel over a range exceeding the truing target surface of the grinding wheel, the output value of the acoustic emission sensor is a part of the entire truing target surface of the grinding wheel. in until a first threshold value, it performs a first truing machining at low truing precision truing conditions,
Next, when the truer is moved relative to the same truing target surface relative to the grinding wheel over a range exceeding the truing target surface of the grinding wheel, the output value of the acoustic emission sensor However, until the second threshold is reached over the entire truing target surface of the grinding wheel, the second truing process is performed under the truing condition with higher truing accuracy than the first truing process,
Next, a third truing process is performed on the same truing target surface under a truing condition with higher truing accuracy than the second truing process.
It is.

  In the truing method of the above means, rough shaping is performed in a plurality of stages of the first truing process and the second truing process under truing conditions with low truing accuracy, and then the third truing condition with high truing accuracy is performed. By truing processing, it is possible to realize reshaping with a desired dimensional accuracy. Here, by performing the first truing process under the truing condition with the lowest truing accuracy in rough reshaping, it is possible to further improve the reshaping efficiency. Then, by the second truing process having higher truing accuracy than the first truing process, it is possible to perform a reshaping that has been finished to some extent prior to the third truing process.

  In the truing method having the above-described configuration, in each of the first truing process, the second truing process, and the third truing process, among setting items of various truing conditions such as a feed speed, a cutting amount, and a truer circumferential speed ratio, It is sufficient to change at least one setting item, but by changing a plurality of setting items, it is possible to realize more efficient reshaping in the first truing process or the second truing process. In particular, by changing a plurality of setting items of the truing condition between the first truing process and the second truing process, it is possible to accurately improve the efficiency of rough shaping in the first truing process.

  The first threshold value and the second threshold value may be set to different values, or may be set to the same value. Here, when the same value is set, for example, as described in the fifth means described later, by changing the condition for determining that the threshold value has been reached, the end of the first truing process and the end of the second truing process Can be determined individually. Further, when setting to different values, the first threshold value may be set to a value lower than the second threshold value, or may be set to a higher value, and each value includes the first truing process. Each of the second truing process and the second truing process may be appropriately set so that the desired truing process is reliably completed.

  The first truing process is intended to reshape the deformed grinding surface roughly with more emphasis on the efficiency than the second truing process. If rough reshaping is excessively performed as a whole, there is a possibility that abrasive grains that can still withstand use are dropped unnecessarily, or pores that are well open are crushed unnecessarily.

  Therefore, if the first truing process is terminated on condition that the output value of the acoustic emission sensor reaches the threshold value in a part of the entire truing target surface of the grinding wheel, rough reshaping is excessively performed. Can be prevented, and the occurrence of the above-described problems can be suppressed.

  On the other hand, the second truing process is intended to give a certain degree of finishing to the shaping prior to the subsequent third truing process. If reshaping is not completed and there is insufficient reshaping, there is a possibility that a trouble that a reshaping with a desired dimensional accuracy cannot be realized depending on the subsequent third truing process.

  Therefore, if the second truing process is terminated on the condition that the output value of the acoustic emission sensor reaches the threshold value over the entire truing target surface of the grinding wheel, there will be a lack of reshaping. It can prevent, and it can control that the above-mentioned trouble arises.

As a third hand stage,
In any of the "first or second hand stage,
The truing condition is at least one of a feed speed or a cutting amount, and a truing condition having a low truing accuracy is set to a fast feed speed or a large cutting amount, while a truing condition having a high truing accuracy is set to a slow feeding speed or a low cutting depth. A truing method of a grinding wheel characterized by a quantity "
It is good.

  The truing method with the above configuration includes items for truing conditions that are changed between low-precision truing processing and high-precision truing processing, or items for truing conditions that are changed between first truing processing, second truing processing, and third truing processing. In the truing condition with low truing accuracy, the truing processing time under the truing condition with low truing accuracy can be shortened accurately by increasing or increasing the feed speed or cutting depth. Therefore, it is possible to accurately improve the reshaping efficiency.

As a fourth hand stage,
In either of "a 1-3 hand stage,
A truing method for a grinding wheel characterized by repeating a truing process a predetermined number of times with the same truing condition at the final stage of the whole truing ”
It is good.

  Truing must eventually complete both a high dimensional accuracy correction of the grinding surface and a good sharpness regeneration of the abrasive grains. Therefore, in the truing method having the above-described configuration, at the final stage of truing, by repeating the truing process a predetermined number of times with a constant truing condition, the dimensional accuracy of the grinding surface is corrected, and the sharpness of the abrasive grains is improved. Both playbacks will be completed. Therefore, according to the truing method having the above-described configuration, it is possible to achieve a high degree of dimensional accuracy and good sharpening by the final truing process.

  Here, in the truing process at the final stage, a truing condition with the highest truing accuracy may be set. In addition, since a certain amount of reshaping has been completed prior to the truing process at the final stage, it is possible to set truing conditions that place greater emphasis on the accuracy of sharpening that regenerates the sharpness rather than the reshaping efficiency. By setting such a truing condition, a truing method that can accurately reproduce a good sharpness can be obtained.

  Note that the truing process of a predetermined number of times with the same truing condition at the final stage in the entire truing may be the high-precision truing process in the first means, or a separate truing process performed after the high-precision truing process. There may be. Further, it may be a third truing process in the fourth means, or a separate truing process performed after the third truing process.

  As described above, according to the present invention, it is possible to provide a truing method for a grinding wheel that can not only reshape efficiently but also perform accurate truing without excessively removing the grinding wheel.

  Next, an example of an embodiment of a truing method for a grinding wheel 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) as an apparatus for realizing a truing method for a grinding wheel according to the present invention. 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 disc 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, the control device 60, when performing truing, various devices such as a grindstone shaft driving device, a truer rotation driving device, an X-axis driving device, and a Z-axis driving device so that truing processing is performed under a predetermined truing condition. In addition, the detection signal output from the AE sensor 52 is monitored, and “the truing condition is low under low truing accuracy until the output value of the acoustic emission sensor reaches a threshold value. After performing an accurate truing process, the output value of the acoustic emission sensor is set to the first threshold value. The first truing process is performed under truing conditions with low truing accuracy until Next, the second truing process is performed on the same truing target surface under the truing condition with higher truing accuracy than the first truing process until the output value of the acoustic emission sensor reaches the second threshold value. Then, the third truing process is performed on the same truing target surface under a truing condition with a higher truing accuracy than the second truing process. "

  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). Here, the truer peripheral speed ratio is a ratio of the peripheral speed of the truer T to the peripheral speed of the grinding wheel S, and is indicated by a value of “(surrounder speed of the truer) / (peripheral speed of the grinding wheel)”. is there. Further, the rotation direction of the truer T is usually opposite to the rotation direction of the grinding wheel S so that the contact portion with the grinding wheel S moves in the same direction as the grinding wheel S. In the circumferential speed ratio, the ratio of the circumferential speed of the grinding wheel S and the circumferential speed of the truer T that rotate relatively in this way is represented by “+ value (plus value)”.

  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.

  In the above example, in relation to the rough truing process and the intermediate finish truing process, the rough truing process corresponds to the “low-precision truing process”, and the threshold value 1 corresponds to the “threshold value for determining the end of the low-precision truing process”. In addition, the truing process with intermediate finish can be regarded as a truing method corresponding to “high-precision truing process”. On the other hand, in the relationship between the finishing truing process and the finishing truing process, the finishing truing process corresponds to “low precision truing process”, and the threshold value 2 corresponds to the “threshold value for determining the end of low precision truing process”. Finishing truing can also be regarded as a truing method equivalent to “high-precision truing”.

  Also, in relation to rough truing, intermediate finish truing, and finish truing, rough truing is “first truing” and intermediate truing is “second truing”. Corresponds to “third truing process”, threshold value 1 corresponds to “first threshold value”, and threshold value 2 corresponds to “second threshold value”.

  As mentioned above, although the truing method of the grinding wheel which concerns on 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 truing method according to the present invention can be realized not only by a cylindrical grinder provided with a truing device but also by other types of grinders provided with a truing device. 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 whole truing is composed of three types of truing, such as rough truing, intermediate finish truing, and finish truing, but rough truing is omitted or intermediate finish truing is performed. It may be omitted.

  In the rough truing process, rough shaping may be performed by setting the truer speed ratio to a negative value. Furthermore, in the rough truing process, the truer truing speed ratio may be set to a small value, and in the intermediate finishing truing process and the finishing truing process, the truer peripheral speed ratio may be set to the same value, and may be set to a larger value than the rough truing process.

  By the way, as the truer peripheral speed ratio in the final stage truing process constituted by the finish truing process, “1” is set to “0.5 to 0.9”, preferably “0.7 to 0.9”. As a large value close to “,” the grinding wheel may be crushed favorably by applying a large destructive force by the truer to the grinding wheel so that the sharpness can be accurately reproduced. And as a truer speed ratio in the truer truing process such as rough truing process and intermediate finish truing process, a smaller value (including a negative value) than the peripheral speed ratio in the finish truing process You only have to set it.

  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. In particular, when the threshold value for determining the end of the rough truing process is set lower than the threshold value for determining the end of the medium finish truing process, it is possible to accurately determine the end of the rough truing process. In addition, it is preferable to reduce the noise output value by slowing the peripheral speed of the grinding wheel until it is determined that the rough truing process has been completed.

It is a top view which shows an example of a grinding machine as an apparatus which implement | achieves the truing method 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)

Monitor the output value of the acoustic emission sensor that outputs the acoustic emission generated when the grinding wheel and the truer come into contact with each other,
When the truer is moved relative to the grinding wheel over a range exceeding the truing target surface of the grinding wheel, the output value of the acoustic emission sensor is a part of the entire truing target surface of the grinding wheel. in reaching a threshold, after the low-precision truing machining at low truing precision truing conditions, and performing high-precision truing machining at high truing precision truing conditions for the same truing target surface The truing method of a grinding wheel. Monitor the output value of the acoustic emission sensor that outputs the acoustic emission generated when the grinding wheel and the truer come into contact with each other,
When the truer is moved relative to the grinding wheel over a range exceeding the truing target surface of the grinding wheel, the output value of the acoustic emission sensor is a part of the entire truing target surface of the grinding wheel. The first truing process is performed under truing conditions with low truing accuracy until the first threshold is reached in
Next, when the truer is moved relative to the same truing target surface relative to the grinding wheel over a range exceeding the truing target surface of the grinding wheel, the output value of the acoustic emission sensor However, until the second threshold is reached over the entire truing target surface of the grinding wheel, the second truing process is performed under the truing condition with higher truing accuracy than the first truing process,
Next, the third truing process is performed on the same truing target surface under the truing condition with higher truing accuracy than the second truing process.
A truing method of a grinding wheel characterized by the above . The truing condition is at least one of a feed speed or a cutting amount, and a truing condition having a low truing accuracy is set to a fast feed speed or a large cutting amount, while a truing condition having a high truing accuracy is set to a slow feeding speed or a low cutting depth. The truing method for a grinding wheel according to claim 1 or 2, wherein the amount is an amount . The truing method for a grinding wheel according to any one of claims 1 to 3, wherein a truing process is repeated a predetermined number of times with the same truing condition in a final stage of the entire truing.

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