JP2009214217A - Grinding wheel distal end position correction method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding wheel distal end position correction method and a device capable of always correcting a distal end position of a grinding wheel at high accuracy. <P>SOLUTION: The grinding wheel distal end position correction device 30 is provided with: a grinding wheel base position detection means 49 for detecting a present position relative to a reference point of the grinding wheel base 20; an approaching detection means 32 or a contact detection means 33 for detecting that the grinding wheel approaches or is contacted with a surface to be cut of a fixture 31 to be cut; and a surface to be cut measurement means 34 for measuring a distance from the reference point of the surface to be cut. When it is detected that the grinding wheel approached or is contacted with the surface to be cut of the fixture to be cut, the present position of the grinding wheel base is detected and memorized as a cutting starting position. The grinding wheel base advances from the cutting starting position by a set cutting-in amount and the grinding wheel cuts the surface to be cut. Thereafter, a distance from the reference point of the surface to be cut is measured, and a distal end position of the grinding wheel relative to the reference point is corrected based on the cutting starting position of the grinding wheel, the set cutting-in amount and the distance from the reference point of the surface to be cut after cutting. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a grinding wheel tip position correcting method and apparatus for correcting the tip position of a grinding wheel.

  In processing a single workpiece with a general-purpose cylindrical grinder, an operator sends the grinding wheel to the workpiece side in a state where the grinding wheel is stopped to bring the grinding wheel outer peripheral surface into contact with the workpiece surface. Then, the grinding wheel base is advanced from the position coordinates at that time by a set cutting amount, the workpiece is temporarily ground, and the outer diameter of the grinding portion is measured to obtain and correct the tip position of the grinding wheel. . However, the feeding of the grinding wheel, the temporary grinding of the workpiece, and the dimension measurement are all manual operations of the operator, and thus it takes time. In addition, the contact alignment accuracy may change depending on the skill level of the operator or the thermal displacement of the cylindrical grinding machine, and the tip position of the grinding wheel may not be accurately obtained and corrected.

Therefore, in the grinding wheel tip position measuring device in the grinding machine described in Patent Document 1, the grinding wheel on the grinding wheel base that has reached two different specific positions in the feeding direction of the grinding wheel head feed shaft is detected by laser light without contact. Then, the diameter of the grinding wheel is calculated based on the detected information. As a result, the tip position of the grinding wheel can be accurately obtained and corrected.
JP 2001-38619 A (paragraphs [0018] to [0020], FIG. 2)

  In the thing described in patent document 1, since the laser beam is used, the outermost diameter of a grinding wheel will be detected. For this reason, if there is a wear part on the surface of the grindstone, or if the grindstone outer shape is a crowning shape, an error occurs in the calculated diameter of the grinding wheel, and the tip position of the grinding wheel is accurately obtained and corrected. It may not be possible.

  An object of the present invention is to provide a grinding wheel tip position correcting method and apparatus capable of always accurately correcting the tip position of a grinding wheel.

  In order to solve the above-mentioned problem, the structural feature of the invention according to claim 1 is a method of correcting the tip position of a grinding wheel rotatably supported on a grinding wheel table using a tool to be ground, Rotating the grinding wheel to advance the grinding wheel head toward the ground surface of the jig to be ground, and detecting that the grinding wheel has approached or contacted the ground surface by means of proximity detection means or contact detection means, When the approach detection means or the contact detection means detects that the grinding wheel has approached or contacted the surface to be ground, the current position relative to the reference point of the grinding wheel base is detected by the grinding wheel base position detection means, and the grinding start position The grinding wheel is moved forward from the grinding start position by a set cutting amount, and the grinding wheel is ground on the grinding surface of the grinding tool, and then the grinding surface is moved from the reference point of the grinding surface. Study distance The tip position of the grinding wheel relative to the reference point is measured based on the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding. It is to correct.

  In order to solve the above-mentioned problem, the structural feature of the invention described in claim 2 is a method for correcting the tip position of a grinding wheel rotatably supported on a grinding wheel table by using a jig to be ground, The grinding wheel is rotated to advance the grinding wheel base at a rapid feed rate toward the surface to be ground of the jig to be ground, and the approach detection means detects that the grinding wheel has approached the surface to be ground, and the grinding wheel When the approach detection means detects that the vehicle has approached the surface to be ground, the wheel head is advanced toward the surface to be ground at a slow feed rate, and the wheel has been in contact with the surface to be ground Is detected by the contact detection means, the current position relative to the reference point of the grinding wheel base is detected by the grinding wheel base position detection means and stored as a grinding start position, and the grinding wheel base is advanced by a set cutting amount from the grinding start position. Let me After grinding the grinding surface of the grinding tool on the grinding wheel, the distance from the reference point of the grinding surface is measured by the grinding surface measuring means, the grinding start position of the grinding wheel, and the setting cut The tip position of the grinding wheel relative to the reference point is corrected based on the amount of insertion and the distance from the reference point of the ground surface after grinding.

  The structural feature of the invention according to claim 3 is that, in claim 1 or 2, the fact that the grinding wheel has approached the surface to be ground of the tool to be ground is between the grinding wheel and the surface to be ground. The dynamic pressure generated by the supplied coolant is detected by the coolant dynamic pressure detecting means.

  The structural feature of the invention according to claim 4 is that, in claim 1 or 2, the fact that the grinding wheel is in contact with the tool to be ground is generated by contact between the grinding wheel and the tool to be ground. The wave is detected by the AE sensor.

  The structural feature of the invention described in claim 5 is a device for correcting the tip position of a grinding wheel rotatably supported on a grinding wheel table by using a tool to be ground, and presently with respect to a reference point of the grinding wheel table Grinding wheel position detecting means for detecting the position, approach detecting means or contact detecting means for detecting that the grinding wheel approaches or contacts the surface to be ground of the tool to be ground, and the workpiece ground by the grinding wheel. A surface to be ground measuring means for measuring a distance from the reference point of the surface to be ground of a grinding jig, and the approach detecting means or the contact detecting means detecting that the grinding wheel has approached or contacted the surface to be ground. The current position of the wheel head relative to the reference point is detected by the wheel head position detecting means and stored as a grinding start position, the wheel head is advanced from the grinding start position by a set cutting amount, and the wheel is moved to the grinding wheel. After grinding the ground surface of the grinding jig, the distance from the reference point of the ground surface is measured by the ground surface measuring means, the grinding wheel starting position, the set cutting depth, and after grinding And a control device that corrects the tip position of the grinding wheel with respect to the reference point based on the distance of the surface to be ground from the reference point.

  The structural feature of the invention described in claim 6 is a device for correcting the tip position of the grinding wheel rotatably supported on the grinding wheel table by using a tool to be ground, and presently with respect to a reference point of the grinding wheel table Grinding wheel position detecting means for detecting the position, proximity detecting means for detecting that the grinding wheel approaches the surface to be ground of the tool to be ground, and the grinding wheel in contact with the surface to be ground of the tool to be ground Contact detecting means for detecting this, ground surface measuring means for measuring the distance from the reference point of the ground surface of the grinding tool ground by the grinding wheel, and rotating the grinding wheel to rotate the grinding wheel When the platform is advanced at a rapid feed rate toward the grinding surface of the jig to be ground, and the approach detection means detects that the grinding wheel has approached the grinding surface, the grinding wheel is moved at a slow feed rate. Advance toward the ground surface When the contact detection means detects that the grinding wheel has contacted the surface to be ground, the current position with respect to the reference point of the grinding wheel base is detected by the grinding wheel base position detection means and stored as a grinding start position, The grindstone table is moved forward from the grinding start position by a set depth of cut, and the grinding wheel is ground on the ground surface of the grinding tool, and then the distance from the reference point of the ground surface is measured. The tip position of the grinding wheel relative to the reference point based on the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding, measured by a grinding surface measuring means And a control device for correcting the above.

  According to a seventh aspect of the present invention, in the fifth or sixth aspect, the approach detection unit is generated by a coolant supplied between the grinding wheel and a surface to be ground of the grinding tool. This is a coolant dynamic pressure detecting means for detecting the dynamic pressure.

  According to an eighth aspect of the present invention, in the fifth or sixth aspect, the contact detecting means is an elastic wave detecting means for detecting that the grinding wheel has contacted the tool to be ground by elastic waves. That is.

  According to the invention according to claim 1, when it is detected that the grinding wheel approaches or contacts the surface to be ground of the grinding tool, the current position with respect to the reference point of the grinding wheel base is detected and stored as the grinding start position. The grindstone is moved forward from the grinding start position by a set cut amount, and the grinding wheel is actually ground by the grinding wheel. Then, measure the distance from the reference point of the surface to be ground, based on the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding Since the tip position of the grinding wheel relative to the reference point is corrected, the tip position of the grinding wheel can be automatically corrected with high accuracy.

  According to the second aspect of the present invention, when it is detected that the grinding wheel has approached the surface to be ground of the tool to be ground, the grinding wheel base is advanced toward the surface to be ground at a slow feed speed, When it is detected that the surface to be ground is touched, the current position with respect to the reference point of the grinding wheel base is detected and stored as a grinding start position, and the grinding wheel base is advanced from the grinding start position by a set cutting amount, Since the grinding wheel is ground by the grinding wheel, the time until the grinding wheel approaches the grinding surface can be shortened, and the idle grinding time until contact can be shortened. Then, the distance from the reference point of the ground surface that is actually ground is measured, and the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding Since the tip position of the grinding wheel relative to the reference point is corrected based on the above, the tip position of the grinding wheel can be automatically and accurately corrected in a short time.

  According to the invention which concerns on Claim 3, the said grinding wheel approached the said grinding surface by measuring the dynamic pressure which generate | occur | produces with the coolant supplied between the grinding wheel and the grinding surface of the to-be-ground jig. Detect that. As a result, it is possible to accurately detect that the grinding wheel is very close to the surface to be ground in a non-contact state, so that the tip position of the grinding wheel can be corrected with higher accuracy in a short time.

  According to the invention which concerns on Claim 4, since the elastic wave is detected and the contact with a grinding wheel and a dynamic pressure detection jig is detected, when grinding the to-be-ground surface of a to-be-ground jig only the set cutting amount, It is possible to make the grinding start position of the grindstone more accurate. Therefore, the tip position of the grinding wheel can be corrected with higher accuracy.

  According to the invention of claim 5, when it is detected that the grinding wheel has approached or contacted the surface to be ground of the tool to be ground, the current position with respect to the reference point of the grinding wheel base is detected and stored as the grinding start position. . The grinding wheel base is advanced from the grinding start position by the set cutting amount, and the grinding wheel grinds the surface to be ground. Then, the distance from the reference point of the surface to be ground is measured, based on the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding The tip position of the grinding wheel with respect to the reference point is corrected. In this way, it is possible to provide a grindstone tip position correcting device capable of automatically and accurately correcting the tip position of the grinding wheel.

  According to the invention of claim 6, when it is detected that the grinding wheel has approached the surface to be ground of the jig to be ground, the grinding wheel base is advanced toward the surface to be ground at a slow feed rate, and the grinding wheel is When it is detected that the surface to be ground is in contact, the current position with respect to the reference point of the grinding wheel base is detected and stored as the grinding start position. Since the grinding wheel head is advanced from the grinding start position by the set cutting amount, and the grinding wheel grinds the surface to be ground, the time until the grinding wheel approaches the surface to be ground is shortened, and the time until the wheel contacts Grinding time is shortened. Then, the distance from the reference point of the ground surface to be actually ground is measured, the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding The tip position of the grinding wheel relative to the reference point is corrected based on the above. In this way, it is possible to provide a grindstone tip position correcting device capable of automatically and accurately correcting the tip position of the grinding wheel in a short time.

  According to the invention which concerns on Claim 7, the said grinding wheel approached the said grinding surface by measuring the dynamic pressure which generate | occur | produces with the coolant supplied between the grinding wheel and the grinding surface of the to-be-ground jig. Detect that. As a result, it is possible to accurately detect that the grinding wheel is very close to the surface to be ground in a non-contact state. Therefore, a grinding wheel tip position correcting device capable of correcting the tip position of the grinding wheel with higher accuracy in a short time is provided. Can be provided.

  According to the invention according to claim 8, since the elastic wave is detected to detect the contact between the grinding wheel and the dynamic pressure detection jig, the grinding surface of the jig to be ground is ground by the set cutting amount. Since the grinding start position of the grinding wheel base can be made with higher accuracy, it is possible to provide a grinding wheel tip position correcting device capable of correcting the tip position of the grinding wheel with higher accuracy.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B are a top view and a front view showing a part of the entire grinding machine provided with a grindstone tip position correcting device.
A table 12 is guided and supported on the bed 11 of the grinding machine 10 so as to be movable in the horizontal X-axis direction, and the grindstone table 20 is guided so as to be movable in the horizontal Z-axis direction orthogonal to the X-axis direction. It is supported. Further, a coolant supply device 60 is arranged. On the table 12, a headstock 13 and a tailstock 14 are arranged to face each other. A grinding wheel 21 is supported on the grinding wheel base 20 so as to be rotatable about an axis parallel to the X-axis direction.

  A spindle 15 on which a center supporting one end of the workpiece W is fitted is rotatably supported on the spindle stock 13, and a center on which a center supporting the other end of the workpiece W is fitted on the tailstock 14. The push shaft 16 is rotatably supported. Further, the spindle stock 13 is provided with a spindle rotating motor 17 that rotates the spindle 15 around a rotation axis O parallel to the X-axis direction, and the tailstock 14 rotates the tailstock shaft 16 synchronously with the spindle 15. A tail push shaft rotating motor 18 is provided. The workpiece W is center-supported at both ends between the main shaft 15 and the tail shaft 16 and is rotated around the rotation axis O by the main shaft and the tail shaft rotation motors 17 and 18. The grinding wheel base 20 has a rotational axis O as a reference point, and a current position with respect to the reference point is detected by a grinding wheel base position detecting means 49 described later. Further, the tailstock 14 is provided with a tool 31 to be ground and a displacement sensor (grinding surface measuring means) 34 constituting the grindstone tip position correcting device 30. The grinding tool 31 is provided with a pressure sensor (approach detection means) 32 for detecting a dynamic pressure generated by the coolant supplied between the grinding wheel 21 and the grinding tool 31 when the grinding wheel 21 approaches the grinding tool 31.

  The grinding wheel 21 is fixed to the grinding wheel shaft 22 via a grinding wheel flange 23, and the periphery is covered with a grinding wheel cover 24. And it is rotated through the belt transmission mechanism 26 by the grindstone drive motor 25. The grinding wheel 21 is composed of, for example, super hard CBN abrasive grains bonded to the outer periphery of a disk-shaped metal core with vitrified bonds. The grindstone outer peripheral surface is a grinding surface 21a parallel to the X-axis direction, and the cylindrical portion of the workpiece W is ground. Further, the grinding wheel shaft 22 is provided with an AE sensor 33 for detecting an elastic wave generated by the contact between the grinding wheel 21 and the jig 31 to be ground, and the AE sensor 33 constitutes a contact detecting means.

  The coolant supply device 60 supplies coolant to a grinding point where the grinding wheel 21 grinds the workpiece W or the tool 31 to be ground. The coolant supply device 60 includes a coolant nozzle 61, a pump 62, a motor 63, a coolant storage tank 64, and the like. The coolant supplied from the pump 62 driven by the motor 63 is controlled in flow rate by a flow control valve (not shown), and is supplied to the grinding point from the coolant nozzle 61 attached to the grinding wheel cover 24 above the grinding wheel 21 for processing. Cool and lubricate the parts. The coolant supplied to the grinding point flows below the bed 11, and after the chips are separated by a magnet separator (not shown), the coolant is returned to the coolant storage tank 64 again.

  A numerical control device 40 for controlling the grinding machine 10 mainly comprises a central processing unit (CPU) 41, a memory 42 for storing various control values and programs, and interfaces 43 and 44. In the memory 42, various data necessary for executing a grinding cycle such as a grinding program, grinding wheel diameter data, grinding wheel width data, dynamic pressure signal threshold data, AE signal threshold data, and grinding target before grinding. Various data necessary for executing the grinding wheel tip position correction such as the measured value of the surface to be ground of the jig 31 are stored. Various data are input to the numerical control device 40 via an input device 45 such as a keyboard or a liquid crystal display. The numerical control device 40 is supplied with a dynamic pressure signal from the pressure sensor 32, an AE signal from the AE sensor 33, and a measurement signal from the displacement sensor 34 via the amplifiers 46, 47, and 48. ing.

The numerical control device 40 is configured to give a drive signal to a Z-axis servomotor 51 that moves the grinding wheel base 20 in the Z-axis direction via the Z-axis motor drive unit 50, and is attached to the Z-axis servomotor 51. The encoder 52 is configured to send the rotational position of the Z-axis servomotor 51, that is, the position of the grindstone table 20 to the Z-axis motor drive unit 50 and the numerical controller 40. The numerical control device 40, the encoder 52, and the like constitute a grinding wheel base position detecting means 49 that detects the current position of the grinding wheel base 20 with respect to the rotation axis O (reference point).
The numerical control device 40 is adapted to give a drive signal to an X-axis servomotor 55 that moves the table 12 in the X-axis direction via the X-axis motor drive unit 54, and is attached to the X-axis servomotor 55. The encoder 56 is configured to send the rotational position of the X-axis servomotor 55, that is, the position of the table 12 to the X-axis motor drive unit 54 and the numerical controller 40.

  Then, the numerical controller 40 drives the servo motors 51 and 55 based on the deviation between the target position command of the NC program stored in the memory 42 and the current position signal from the encoders 52 and 56, respectively, and the table 12 and the grinding wheel base Positioning control 20 is performed at each target position. The numerical control device 40 counts the number of workpieces W processed by the grinding wheel 21. When the number of workpieces reaches a predetermined value and the grinding surface of the grinding wheel 21 wears and the tip position is displaced more than an allowable value, the tip of the grinding wheel. Command position correction.

Next, the grindstone tip position correcting device 30 will be described in detail mainly with reference to FIGS. 2 and 3.
2A and 2B are a front view and a right side view showing the periphery of the jig 31 to be ground in FIG. 1, and FIGS. 3A and 3B show the periphery of the grinding wheel 21 in FIG. It is a left side view and a front view.
In the grinding wheel tip position correcting method and apparatus according to the present embodiment, the grinding wheel 31 is ground by the grinding wheel 21 and then the distance from the reference point of the grinding surface of the grinding tool 31 is measured. 21, that is, the tip position of the grinding surface to be ground in contact with the grinding tool 31 (work W) in the outer peripheral portion of the grinding wheel 21 is detected and corrected. In addition to the jig 31 to be ground, the apparatus 30 that realizes such a grinding wheel tip position correction includes a pressure sensor 32, an AE sensor 33, a displacement sensor 34, and a grinding wheel base position detection means 49.

As shown in FIGS. 1 and 2, the tool 31 to be ground is fitted to the tailstock 14 by a center hole 31 h and fixed to the tailstock 14 by a set screw 35, and the tip position of the grinding wheel 21 is determined. It is a jig that is ground to compensate. The to-be-ground jig 31 is formed in a shape in which a large-diameter semi-cylindrical portion 31a and a small-diameter semi-cylindrical portion 31b are coaxially integrated, and an outer peripheral surface 31f of the large-diameter semi-cylindrical portion 31a is ground. Surface. The tool 31 to be ground is fixed to the tailstock shaft 14 so that the large-diameter semi-cylindrical portion 31a is coaxial with the rotation axis O.
Furthermore, a hole 31c (for example, φ0.75 mm to φ1 mm) for measuring the dynamic pressure of the coolant is drilled in the tool 31 to be ground from the central portion of the outer peripheral surface 31f of the large-diameter semicylindrical portion 31a downward. Has been. A pressure sensor 32 is inserted and fixed in a step portion 31d between the large-diameter semi-cylindrical portion 31a and the small-diameter semi-cylindrical portion 31b, and a pore 31c communicates with the pressure-sensitive portion at the tip of the pressure sensor 32. .

  The pressure sensor 32 is an approach detection unit that detects that the grinding wheel 21 has approached the surface to be ground of the tool 31 to be ground. As the pressure sensor 32, for example, there is one using a semiconductor strain gauge. When the grinding wheel 21 approaches the jig 31 to be ground, the dynamic pressure generated by the coolant interposed therebetween is introduced into the pressure sensor 32 through the pore 31c opened in the outer peripheral surface 31f of the large-diameter semi-cylindrical portion 31a. Thus, the degree of approach of the grinding surface 21a of the grinding wheel 21 to the outer peripheral surface 31f of the large-diameter semicylindrical portion 31a can be detected.

  The AE sensor 33 is a contact detection unit that detects that the grinding wheel 21 has contacted the surface to be ground of the tool 31 to be ground. As shown in FIG. 3, the AE sensor 33 includes a signal sensor unit 33a and a signal receiver unit 33b. The signal sensor unit 33a is coaxially fixed to the tip of the grindstone shaft 22 and rotates together with the signal receiver unit. 33b is attached to the inner surface of the grindstone cover 24 so as to face the signal sensor portion 33a at a predetermined interval (for example, 0.5 mm to 1 mm). When the signal receiver 33b receives a detection signal transmitted when the AE sensor 33 detects an elastic wave and transmits the detection signal to the numerical control device 40, the grinding surface 21a of the grinding wheel 21 has a large diameter half of the jig 31 to be ground. The contact with the outer peripheral surface 31f of the cylindrical portion 31a is detected.

  The displacement sensor 34 is a to-be-ground surface measuring means for measuring the displacement of the to-be-ground surface of the to-be-ground jig 31 ground by the grinding wheel 21. As shown in FIG. 2, the displacement sensor 34 is shown in FIG. It is attached to an arm 34a extending from the upper part of the tailstock 14 to the upper side of the jig 31 to be ground. As the displacement sensor 34, for example, there is one using an eddy current sensitive element. By measuring the displacement of the outer peripheral surface 31f of the large-diameter semi-cylindrical portion 31a of the ground jig 31 after grinding by the displacement sensor 34, the distance from the rotation axis O (reference point) of the ground surface of the ground jig 31 Can be measured.

Hereinafter, the grindstone tip position correcting process by the numerical controller 40 will be described based on the flowchart shown in FIG.
Here, when the grinding wheel tip position correction is executed for the first time, or when the grinding tool 31 is replaced with a new one, the distance from the rotation axis O of the grinding surface of the grinding tool 31 is measured, and the grinding surface The first measured value a1 measured by the displacement sensor 34 and the initial distance L1 from the rotation axis O of the surface to be ground of the tool 31 to be ground are stored in a predetermined storage area of the memory 42.

  When the grindstone tip position correction process is started, the tailstock shaft 14 is rotated so that the opening of the fine hole 31 c of the outer peripheral surface 31 f faces the tip position of the grindstone 21. In step 102, the X-axis servo motor 55 is driven to control the movement of the table 12 in the X-axis direction. As shown in FIG. 1A, the grinding surface 21a of the grinding wheel 21 is the outer peripheral surface 31f of the jig 31 to be ground. Is positioned at the grindstone tip position correction start position that faces the wheel. Next, at step 104, the grinding wheel drive motor 25 is driven to rotate the grinding wheel 21, and the motor 63 is driven to supply coolant to the tip position of the grinding wheel 21. In step 106, the Z-axis servo motor 51 is driven to advance the grindstone table 20 toward the table 12 side.

  In step 108, when the grinding wheel 21 approaches the tool 31 to be ground, the dynamic pressure generated by the coolant supplied therebetween is transmitted to the pressure sensitive part of the pressure sensor 32 through the pore 31c. The output dynamic pressure signal as shown in FIG. 5 is input to the numerical controller 40. It is determined whether or not the dynamic pressure signal level (hereinafter referred to as a dynamic pressure value) has reached a preset threshold value p shown in FIG. 5. If the dynamic pressure value has not yet reached the set threshold value p, step 108 is performed. The determination result in NO is NO, the process returns to step 106, and the advancing operation of the grindstone table 20 by the Z-axis servomotor 51 is continued. The set threshold value p is a value when the grinding surface 21a of the grinding wheel 21 is positioned immediately before the outer peripheral surface 31f of the jig 31 to be ground, for example, 10 μm before. It should be noted that the grindstone tip position correction processing time can be shortened by fast-forwarding the forward movement of the grindstone table 20 until the set threshold value p is reached.

  On the other hand, when the dynamic pressure value reaches the set threshold p, the determination result in step 108 is YES, and the process proceeds to the next step 110. In step 110, a grinding cycle in which the tailstock shaft 14 is reciprocated by a predetermined angle by the tailstock shaft rotation motor 18 and the large-diameter semicylindrical portion 31a is ground by the grinding wheel 21 by the set cutting amount g1 is started. The feed speed at which the grinding wheel base 20 is advanced by the Z-axis servomotor 51 at this time is a slow feed speed that is slower than the fast feed speed before the dynamic pressure value reaches the set threshold value p. In step 112, when the AE signal as shown in FIG. 6 output from the AE sensor 33 is input to the numerical controller 40, the AE signal level (hereinafter referred to as AE value) is set in advance as shown in FIG. It is determined whether or not the threshold e is exceeded. If the AE value has not yet exceeded the set threshold value e, the determination result in step 112 is NO, the process returns to step 110, and the advancing operation of the grindstone table 20 by the Z-axis servomotor 51 is continued.

  When the AE value exceeds the set threshold e, the determination result in step 112 is YES, and the grinding surface 21a of the grinding wheel 21 has contacted the outer peripheral surface 31f of the large-diameter semi-cylindrical portion 31a of the tool 31 to be ground. Is detected, and the process proceeds to the next step 114. In step 114, the current position with respect to the reference point of the grindstone table 20 when the AE value exceeds the set threshold value e is detected by the grindstone table position detecting means 49 and stored as a grinding start position in a predetermined storage area of the memory 42. The grinding end position obtained by adding the set cutting amount g1 to the grinding start position is stored in a predetermined storage area of the memory 42. Then, the grinding wheel base 20 is advanced from the grinding start position to the grinding end position, and the large-diameter semi-cylindrical portion 31a is ground. At this time, in order to grind the outer peripheral surface 31f of the large-diameter semi-cylindrical portion 31a, the tailstock shaft 14 is rotated back and forth by a predetermined angle by the tailstock shaft rotation motor 14, and the tool 31 has a fine hole 31c on the outer peripheral surface 31f. It is rotated 90 degrees forward and backward from the center of the opening.

  In step 116, the grinding wheel base 20 is retracted from the table 12, the rotation of the grinding wheel 21 is stopped, and the grinding cycle of the grinding tool 31 is completed. In step 118, the jig 31 is rotated so that the upper portion of the outer peripheral surface 31f of the large-diameter semi-cylindrical portion 31a is positioned directly below the displacement sensor 34. Then, the second measurement value a <b> 2 output from the displacement sensor 34 is input to the numerical controller 40 and stored in a predetermined storage area of the memory 42.

  Subsequently, in step 120, the rotation axis O (of the outer peripheral surface 31f of the large-diameter semi-cylindrical portion 31a after grinding is determined from the difference between the first measurement value a1 and the second measurement value a2 of the outer peripheral surface 31f of the large-diameter semi-cylindrical portion 31a. The distance L2 from the reference point) is calculated by L2 = L1- (a2-a1), and in step 122, the set cutting amount g1 is added to the grinding start position of the grinding wheel base 20 detected by the grinding wheel base position detecting means 49. The finished grinding end position is stored as the distance L2 from the rotation axis O of the tip position of the grinding wheel 21.

  As described above, when the grinding wheel 21 approaches the grinding tool 31, the dynamic pressure of the coolant interposed between the grinding wheel 21 and the grinding surface of the grinding tool 31 is detected to detect the grinding wheel 21 and the grinding target. The approach of the jig 31 with the surface to be ground is detected. Furthermore, elastic waves are detected to detect contact between the grinding wheel 21 and the grinding surface of the grinding tool 31. For this reason, the exact grinding start position of the grinding wheel 21 when grinding the to-be-ground jig 31 with the set cutting amount can be obtained. Furthermore, since the distance from the reference point of the ground surface of the grinding tool 31 after grinding can be accurately calculated based on the measured value of the displacement of the ground surface by the displacement sensor 34, the grinding wheel 21 The tip position can be corrected with high accuracy.

  In the above embodiment, the pressure sensor 32 detects that the grinding wheel 21 has approached the surface to be ground of the jig 31 to be ground, and the AE sensor 33 detects the contact between the two. The position in contact with the surface to be ground is set as the grinding start position, and the grinding wheel base 20 is advanced from the grinding start position by the set cutting amount g1, but the grinding wheel 21 is connected to the large diameter semi-cylindrical portion 31a of the grinding tool 31. A position at which the pressure sensor 32 detects that the outer peripheral surface 31f (surface to be ground) has approached is set as a grinding start position, and the grinding wheel base 20 is advanced from the grinding start position by a set cutting amount g1 to be ground by the grinding wheel 21. The surface to be ground of the jig 31 may be ground.

FIG. 7 is a top view showing a table portion of a grinding machine provided with a grindstone tip position correcting device of another form. The same components as those of the grinding machine 10 in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
In this grinding machine 70, a grinding wheel (not shown) has approached the surface to be ground of the jig 72 to be ground by means of a laser beam detector 71 instead of the pressure sensor 32 and the amplifier 47 used in the grinding machine 10 of FIG. Is configured to detect. And since the laser beam detector 71 is used, it forms in the shape which combined the large diameter semicylindrical part 31a and the small diameter semicylindrical part 31b like the to-be-ground jig 31 used with the grinding machine 10 of FIG. There is no need, and there is no need to drill the pore 31c and the sensor hole 31d. For this reason, the jig 72 to be ground used in the grinding machine 70 may have a simple cylindrical shape.

As shown in FIG. 7, the laser light detection device 71 includes a laser light emitting element 73, a laser light receiving element 74, and an amplifier 75 for laser light.
The laser light emitting element 73 and the laser light receiving element 74 are in the vicinity of the grinding tool 72 on the grinding wheel side on the table 12, and are output from the laser light emitting element 73 and input to the laser light receiving element 74. Is arranged so as to be parallel to the X-axis direction and to pass through a position separated from the outer peripheral surface 72a of the jig 72 to be ground by a predetermined distance.

  According to such a configuration, the grinding surface of the grinding wheel approaching the outer peripheral surface 72a (surface to be ground) of the grinding tool 72 shields the laser beam, so that the grinding surface of the grinding wheel at the time of the shielding is It can be detected that it is positioned immediately before contacting the outer peripheral surface 72a of the jig 72 to be ground, for example, 10 μm before. Therefore, even if the laser light detection device 71 is used, the same effect as that of the pressure sensor 32 is obtained, so that the tip position of the grinding wheel 21 can be corrected with high accuracy.

  When the central angle of the large-diameter semi-cylindrical portion 31a of the jig 31 to be ground exceeds 180 degrees and when the jig to be ground is cylindrical like the jig 72 to be ground, the large-diameter semi-cylindrical portion 31a or the workpiece to be ground The diameter D of the jig 72 may be measured, and half of the diameter D may be the distance L from the rotation axis O of the ground surfaces of the jigs 31 and 72 to be ground. In this case, instead of the non-contact type displacement sensor 34 used in the grinding machine 10 of FIG. 1, a contact-type dimension measuring device 76 as shown in FIG. The diameter of the workpiece 72 is directly measured. The dimension measuring device 76 includes two contactors 77 arranged opposite to each other and a displacement measuring device 78 of the contactor 77. These contactors 77 are configured to be close to and away from each other, and measure the diameter by contacting the large-diameter semi-cylindrical portion 31a or the outer peripheral surface of the jig 72 to be ground.

  In the above-described embodiment, the example in which the contact between the grinding wheel 21 and the tool 31 to be ground is detected by the AE sensor 33 has been described. However, the contact detection means is not particularly limited to the AE sensor. Various types of contact detection means such as means for detecting contact from the vibration of the tool 31 to be ground and means for detecting contact from the power fluctuation (load fluctuation) of the grindstone drive motor 25 can be used.

  Further, the flowchart shown in FIG. 4 is merely an example suitable for carrying out the present invention, and the present invention is not limited to this, and various modes can be used without departing from the gist of the present invention. Of course, it can be taken.

(A), (B) is the top view which shows the whole grinding machine provided with the grindstone front-end | tip position correction apparatus, and the front view which shows a part. (A), (B) is the front view and right view which show the periphery of the to-be-ground jig | tool of FIG. (A), (B) is the left view and front view which show the periphery of the grinding wheel of FIG. It is a flowchart for demonstrating the grindstone front-end | tip position correction process by the numerical control apparatus of FIG. It is a figure which shows a time-dependent change until the dynamic pressure value by the pressure sensor of FIG. 1 becomes a setting threshold value. It is a figure which shows a time-dependent change until the AE value by the AE sensor of FIG. 1 exceeds a setting threshold value. It is a top view which shows the table part of the grinding machine provided with the grindstone front-end | tip position correction apparatus of another form. It is a figure which shows the contact-type dimension measuring apparatus used instead of the displacement sensor of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,70 ... Grinding machine, 14 ... Tailstock, 20 ... Grinding wheel base, 21 ... Grinding wheel, 21a ... Grinding surface, 30 ... Grinding wheel tip position correction device, 31, 72 ... Grinding tool, 31f ... Outer peripheral surface (Grinding surface), 32 ... pressure sensor (approach detection means), 33 ... AE sensor (contact detection means), 34 ... displacement sensor (grinding surface measuring device), 40 ... numerical control device, 49 ... wheel head position detection Means: 60 ... Coolant delivery device, 71 ... Laser light detection device, O ... Rotation axis (reference point), W ... Workpiece.

Claims (8)

A method of correcting the tip position of a grinding wheel rotatably supported on a grinding wheel table using a tool to be ground,
The grinding wheel is rotated to advance the grinding wheel head toward the surface to be ground of the jig to be ground, and the approach detection means or the contact detection means detects that the grinding wheel has approached or contacted the surface to be ground. ,
When the approach detection means or the contact detection means detects that the grinding wheel has approached or contacted the surface to be ground, the current position relative to the reference point of the grinding wheel base is detected by the grinding wheel base position detection means, and the grinding start position Remember as
The grindstone is moved forward from the grinding start position by a set cut amount, and the grinding wheel is ground on the grinding surface of the grinding tool, and then the distance from the reference point of the grinding surface is ground. Measured by surface measuring means,
The tip position of the grinding wheel relative to the reference point is corrected based on the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding. Grinding wheel tip position correction method. A method of correcting the tip position of a grinding wheel rotatably supported on a grinding wheel table using a tool to be ground,
Rotating the grinding wheel to advance the grinding wheel head toward the surface to be ground of the jig to be ground at a fast feed speed, and detecting that the grinding wheel has approached the surface to be ground by an approach detection means;
When the approach detection means detects that the grinding wheel has approached the surface to be ground, the grinding wheel base is advanced toward the surface to be ground at a slow feed rate, and the grinding wheel contacts the surface to be ground. When it is detected by the contact detection means, the current position with respect to the reference point of the wheel head is detected by the wheel head position detection means and stored as a grinding start position,
The grindstone is moved forward from the grinding start position by a set cut amount, and the grinding wheel is ground on the grinding surface of the grinding tool, and then the distance from the reference point of the grinding surface is ground. Measured by surface measuring means,
The tip position of the grinding wheel relative to the reference point is corrected based on the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding. Grinding wheel tip position correction method.   3. The coolant dynamic pressure according to claim 1 or 2, wherein a dynamic pressure generated by the coolant supplied between the grinding wheel and the surface to be ground indicates that the grinding wheel has approached the surface to be ground of the jig to be ground. A method for correcting the tip position of a grindstone, which is detected by detecting means.   3. The grinding wheel tip according to claim 1, wherein an elastic wave generated by the contact between the grinding wheel and the tool to be ground is detected by an AE sensor when the grinding wheel is in contact with the tool to be ground. Position correction method. A device for correcting the tip position of a grinding wheel rotatably supported on a grinding wheel table using a tool to be ground,
A wheel head position detecting means for detecting a current position with respect to a reference point of the wheel head;
An approach detecting means or a contact detecting means for detecting that the grinding wheel approaches or contacts the surface to be ground of the jig to be ground;
A to-be-ground surface measuring means for measuring a distance from the reference point of the to-be-ground surface of the to-be-ground jig ground by the grinding wheel;
When the approach detection means or the contact detection means detects that the grinding wheel has approached or contacted the surface to be ground, the current position relative to the reference point of the grinding wheel base is detected by the grinding wheel base position detection means, and the grinding start position The grinding wheel is moved forward from the grinding start position by a set cutting amount, and the grinding wheel is ground on the grinding surface of the jig to be ground. The grinding wheel is measured with respect to the reference point based on the grinding start position of the grinding wheel, the set cutting depth, and the distance from the reference point of the ground surface after grinding. And a control device for correcting the tip position of the grindstone. A device for correcting the tip position of a grinding wheel rotatably supported on a grinding wheel table using a tool to be ground,
Grinding wheel base position detecting means for detecting a current position with respect to a reference point of the grinding wheel base;
An approach detecting means for detecting that the grinding wheel has approached a surface to be ground of the jig to be ground;
Contact detection means for detecting that the grinding wheel has come into contact with the surface to be ground of the jig to be ground;
A surface to be ground measuring means for measuring a distance from the reference point of the surface to be ground of the jig to be ground ground by the grinding wheel;
When the grinding wheel is rotated to advance the grinding wheel head at a rapid feed rate toward the surface to be ground of the jig to be ground, and the approach detection means detects that the grinding wheel has approached the surface to be ground. The grinding wheel is advanced toward the surface to be ground at a slow feed rate, and when the contact detecting means detects that the grinding wheel has contacted the surface to be ground, the current point relative to the reference point of the grinding wheel base The position is detected by the wheel head position detecting means and stored as a grinding start position, the wheel head is advanced from the grinding start position by a set cutting amount, and the grinding surface of the grinding tool is ground on the grinding wheel. Then, the distance of the ground surface from the reference point is measured by the ground surface measuring means, the grinding start position of the grinding wheel, the set cutting depth, and the ground surface of the ground surface after grinding From the reference point Grinding tip position correcting device characterized by and a control device for correcting the position of the tip of the grinding wheel with respect to the reference point based on away.   In Claim 5 or 6, the said approach detection means is a coolant dynamic pressure detection means which detects the dynamic pressure which generate | occur | produces with the coolant supplied between the said grinding wheel and the to-be-ground surface of the said to-be-ground jig. A grindstone tip position correcting device.   7. The grindstone tip position correcting device according to claim 5, wherein the contact detecting means is an elastic wave detecting means for detecting that the grinding wheel has contacted the tool to be ground by elastic waves.

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