JP2007125644A - Truing device of grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect the truing start reference position of the circular-arc grinding surface of a grinding wheel using a contact detecting means. <P>SOLUTION: This truing device of a grinding wheel includes: a contact detecting means for detecting contact between a truing tool 32 and a grinding wheel 21; a circular-arc grinding surface start reference position detecting means for detecting the truing start reference position of the circular-arc grinding surface 21b of the grinding wheel based upon a signal change of the contact detecting means when the cylindrical grinding surface 21a of the grinding wheel is trued by the relative movement of the grinding wheel and the truing tool using an X-axis direction moving means; and a synchronous control means for synchronously controlling the X-axis direction moving means and a Z-axis moving means to true the circular-arc grinding surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a truing device for a grinding wheel, and more particularly, a truing device capable of accurately detecting a truing start reference position of an arc grinding surface of a grinding wheel having an arc grinding surface at least one end of a cylindrical grinding surface by using a contact detection means. It is about.

In general, in a grinding machine, every time a workpiece is ground by a predetermined number of workpieces, the grinding surface of the grinding wheel is trued with a truing tool. By the way, in a grinding machine equipped with a grinding wheel made of hard abrasive grains such as CBN, the truing tool with respect to the grinding wheel has an accuracy of several microns regardless of a relative position change between the truing tool and the grinding wheel due to thermal displacement or the like. In order to stably control the depth of cut, contact detecting means comprising an AE sensor or the like is provided in a grinding wheel support that supports a grinding wheel or a truing device that supports a truing tool, and the truing tool contacts the grinding surface of the grinding wheel. This is detected based on the AE signal, and the cutting amount of the truing tool with respect to the grinding wheel is controlled based on this contact position. Such a truing device is described in Patent Document 1, for example.
Japanese Patent Laid-Open No. 5-131364 (paragraphs 0002 and 0013, FIG. 1)

  By the way, in the truing device for truing a grinding wheel having an arc grinding surface at least one end of the cylindrical grinding surface, the surface property of the cylindrical grinding surface before truing is detected by a contact detection action as described in Patent Document 1. It can be recognized to some extent, and a minute cutting amount can be given with relatively high accuracy, but the surface properties of the arc grinding surface cannot be recognized at all, and it is not known where to start cutting. Is the current situation.

  Therefore, in the conventional truing device, it is necessary to determine the cutting start position of the arc grinding surface with some allowance, and there is a risk of truing the arc grinding surface with zero cutting for the first few times. On the other hand, even if the truing is performed a set number of times, it is suspicious whether or not the arc grinding surface has been effectively sharpened, resulting in truing more than necessary. Therefore, conventionally, there are problems such as an increase in the truing cycle time and an increase in the tool cost of the grinding wheel.

  The present invention has been made to solve the above-described conventional problems, and provides a truing device that can accurately detect the truing start reference position of the arc grinding surface of the grinding wheel using the contact detection means. To do.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a truing device for truing a grinding wheel having an arc grinding surface at least one end of a cylindrical grinding surface with a truing tool. X-axis direction moving means for relatively moving the wheel in the rotational axis direction of the grinding wheel, Z-axis direction moving means for relatively moving the truing tool relative to the grinding wheel in a direction intersecting the rotational axis direction of the grinding wheel, When truing the cylindrical grinding surface of the grinding wheel by the relative movement of the grinding wheel and the truing tool by the X axis direction movement means by contact detection means for detecting contact between the truing tool and the grinding wheel A crane for detecting a truing start reference position of an arc grinding surface of the grinding wheel based on a signal change of the contact detecting means. Truing start reference position detecting means and truing the arc grinding surface by synchronously controlling the X axis direction moving means and the Z axis direction moving means based on the truing start reference position detected by the truing start reference position detecting means. And a synchronization control means.

  According to a second aspect of the present invention, in the first aspect, the contact detecting means is configured by an AE sensor that outputs an AE signal generated by contact between the truing tool and the grinding wheel.

  According to the first aspect of the present invention, during truing of the cylindrical grinding surface of the grinding wheel, the truing start reference position of the arc grinding surface of the grinding wheel is detected based on the signal change of the contact detecting means, and the detected truing start is detected. The X-axis direction moving means and Z-axis direction moving means are controlled synchronously with the reference position as the base point, so that the arc grinding surface is trued. Therefore, the arc grinding surface is cut regardless of the surface properties of the arc grinding surface. The starting position can be accurately determined, and the circular grinding surface can be trued with high accuracy with the minimum necessary truing cycle. Therefore, the tool cost of the grinding wheel can be reduced, and the truing cycle time can be shortened.

  According to the second aspect of the present invention, the contact detection means is composed of an AE sensor that outputs an AE signal generated by contact between the truing tool and the grinding wheel, and therefore, a relatively simple and inexpensive sensor. The contact between the grinding wheel and the truing tool can be detected.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings. FIG. 1 shows an entire grinding machine 10 equipped with a truing device for a grinding wheel. A table 12 is supported on a bed 11 of the grinding machine 10 so as to be movable in the horizontal X-axis direction. A headstock 13 and a tailstock 14 are disposed on the table 12 so as to face each other, and a chuck 15 for gripping one end of the work W is provided on the headstock 13, and the other end of the work W is provided on the tailstock 14. A center 16 is provided to support the. The workpiece W is supported at both ends by the chuck 15 and the center 16 so as to be rotated around an axis parallel to the moving direction (X-axis direction) of the table 12, and is rotated by the chuck 15.

  On the bed 11, the grindstone table 20 is guided and supported so as to be movable in the horizontal Z-axis direction orthogonal to the moving direction of the table 12. A grinding wheel 21 is supported on the grinding wheel base 20 so as to be rotatable around an axis parallel to the moving direction (X-axis direction) of the table 12. 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. As shown in FIG. 2, the grinding wheel 21 has a cylindrical grinding surface 21a parallel to the moving direction (X-axis direction) of the table 12 and an arc grinding surface 21b connected to one end of the cylindrical grinding surface 21a on the outer peripheral surface. Yes. The grinding wheel 21 is rotationally driven by a grinding wheel drive motor 22 via a belt transmission mechanism to traverse the cylindrical portion W1 of the workpiece W by the cylindrical grinding surface 21a, and at the traverse end, the arc corner of the workpiece W by the arc grinding surface 21b. The portion W2 is ground.

  The table 12 is provided with a truing device 30 for truing the grinding wheel 21. As shown in FIG. 3, the truing device 30 includes a thin-walled cylindrical truing tool 32 for truing the cylindrical grinding surface 21 a of the grinding wheel 21 on a rotatable truer shaft 31, and the truing tool 32 together with the truer shaft 31. It is configured to rotate by a built-in motor (not shown).

  An AE sensor 35 constituting contact detection means is disposed on the grindstone table 20. The AE sensor 35 detects elastic waves (Accostic Emission) generated by contact between the grinding wheel 21 and the truing tool 32. The AE sensor 35 may be disposed at the shaft end of the grinding wheel shaft to which the truing device 30 supporting the truing tool 32 or the grinding wheel 21 is attached in addition to the grinding wheel base 20 described above.

  As shown in FIG. 1, the numerical controller 40 that controls the grinding machine 10 mainly includes a central processing unit 41, a memory 42 that stores various control values and programs, and interfaces 43 and 44. The memory 42 stores various data necessary for executing a grinding process and a truing cycle, such as a grinding process program, a truing program, contact detection position data, truing infeed amount data, and wheel diameter data and wheel width data. ing. Various data are input to the numerical control device 40 via an input device 45. The input device 45 includes a keyboard for inputting data and a display such as a CRT for displaying data. Equipped with equipment. Further, a contact signal (AE signal) from a contact detection means (AE sensor) 35 is input to the numerical control device 40 via an amplifier 46.

  The numerical controller 40 gives a drive signal to the Z-axis servo motor 51 via the Z-axis motor drive unit 50, and the Z-axis servo motor 51 moves the grinding wheel base 20 to the Z-axis via a ball screw (not shown). It is designed to move in the axial direction. The encoder 52 attached to the Z-axis servomotor 51 feeds back the rotational position of the Z-axis servomotor 51, that is, the position of the grinding wheel base 20 to the Z-axis motor drive unit 50 and the numerical controller 40. Further, the numerical controller 40 gives a drive signal to the X-axis servo motor 55 that moves the table 12 in the X-axis direction via the X-axis motor drive unit 54, and the X-axis servo motor 55 omits the illustration. The table 12 is moved in the X-axis direction via the ball screw. The encoder 56 attached to the X-axis servomotor 55 feeds back 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.

  The numerical control device 40 drives the servo motors 51 and 55 according to 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. Are controlled to the target positions.

  The X-axis servomotor 55 and the unillustrated ball screw constitute the X-axis direction moving means 57 in the claims. Similarly, the Z-axis servomotor 51 and the unillustrated ball screw or the like claim The Z-axis direction moving means 58 in FIG.

  The numerical control device 40 counts the number of workpieces W processed by the grinding wheel 21 and instructs a truing operation when the number of workpieces reaches a predetermined value. Hereinafter, the processing of the truing operation by the numerical control device 40 will be described based on the flowcharts shown in FIGS.

  Based on the truing start command, the central processing unit 41 of the numerical control device 40 sequentially executes step 100 and step 200 shown in FIG. 4 to truve the cylindrical grinding surface 21a and the arc grinding surface 21b of the grinding wheel 21. The details of the truing cycle of the cylindrical grinding surface 21a in step 100 are shown in FIG. 5, and the details of the truing cycle of the arc grinding surface 21b in step 200 are shown in FIG. Hereinafter, the flowcharts of FIGS. 4 and 5 will be described in order with reference to FIG.

  In FIG. 5, first, in step 102, the contents of the counter N that counts the number of truing traverses are cleared to 0. Next, in step 104, the X-axis and Z-axis servomotors 55 and 51 are driven to The grinding wheel base 20 is moved and controlled in the X-axis direction and the Z-axis direction, and the cylindrical grinding surface 21a of the grinding wheel 21 is contact detection start position corresponding to the outer periphery of the truing tool 32 of the truing device 30 (in FIG. Position). Next, in Step 106, the truer shaft 31 and the grinding wheel 21 are driven to rotate, and the Z-axis servo motor 51 is driven to advance the grinding wheel base 20 in the Z-axis direction toward the table 12 side.

  In step 108, it is determined whether or not a contact signal is output from the contact detection means (AE sensor) 35. If no contact signal is output yet (when the determination result is N0), the process returns to step 106. Then, the forward movement of the grinding wheel base 20 by the Z-axis servo motor 51 is continued. When the cylindrical grinding surface 21a of the grinding wheel 21 comes into contact with the outer peripheral surface of the truing tool 32 and a contact signal is output from the contact detection means 35 as shown by a two-dot chain line in FIG. The result is YES, and the process proceeds to the next step 110.

  In step 110, the position Z1 in the Z-axis direction where the contact is detected is stored in a predetermined storage area of the memory 42, and the advancement of the grindstone table 20 is stopped. Next, at step 112, the grindstone table 20 is retracted by a predetermined amount (ZA) in the Z-axis direction by the Z-axis servomotor 51, and the table 12 is moved by a predetermined amount (XA) in the X-axis direction by the X-axis servomotor 55 ( As shown by the solid line in FIG. 3B, one end of the cylindrical grinding surface 21a of the grinding wheel 21 (the end opposite to the arc grinding surface 21b) corresponds to the side of the truing tool 32. Is positioned at the truing start position.

  Subsequently, in step 114, the grinding wheel base 20 is advanced in the Z-axis direction by the Z-axis servo motor 51 by the predetermined amount (ZA), and the grinding wheel 21 is stored in the contact detection position (Z-axis) stored in step 108 described above. Positioned in the direction position Z1). Next, at step 116, the grinding wheel base 20 is advanced by the truing cutting amount ΔZ stored in the memory 42, whereby the grinding wheel 21 is moved with respect to the truing tool 32 as shown by a two-dot chain line in FIG. Is cut by the cutting amount ΔZ. In the following step 118, the table 12 is traversed by a predetermined amount by the X-axis servomotor 55, and the cylindrical grinding surface 21a of the grinding wheel 21 is trued by the cutting amount ΔZ by the truing tool 32. In this way, the first truing is completed by one reciprocation of the table 12.

When the first truing is finished, in step 120, 1 is added to the counter N for counting the number of traverses, and then in step 122, it is determined whether or not the content of the counter N has reached the set number NA. When the set number of times has not been reached (when the determination result is NO), the process returns to step 116 and the grinding wheel 21 further cuts into the truing tool 32 as indicated by the two-dot chain line in FIG. The grinding surface 21a of the grinding wheel 21 is trued by the traverse of the table 12 (step 118).
Thus, when the cylindrical grinding surface 21a of the grinding wheel 21 is trued by the set number of times by the truing tool 32, the determination result in step 122 becomes YES, and the routine proceeds to step 124. In step 124, the table 12 is moved (leftward) in the X-axis direction, and the grinding surface 21a of the grinding wheel 21 is trued by the traverse of the table 12 as described above, but the table 12 is moved in the X-axis direction. In step 126, the state of the contact signal output from the contact detection means (AE sensor) 35 is monitored to determine whether or not the contact signal has changed from on to off.

  That is, in a state where the cylindrical grinding surface 21a of the grinding wheel 21 is cut and trued with respect to the truing tool 32, a contact signal (ON signal) is continuously output from the contact detection means (AE sensor) 35. However, as shown in FIG. 3C, when the truing tool 32 passes through the cylindrical grinding surface 21a of the grinding wheel 21 and reaches a position corresponding to the arc grinding surface 21b, the contact detection means (AE sensor) 35 The contact signal disappears and the output turns off.

  When the output of the contact detection means (AE sensor) 35 changes from on to off, the determination result in step 126 is YES, and in the next step 128, the output of the contact detection means (AE sensor) 35 changes in the X-axis direction. The position X1 is stored in a predetermined storage area of the memory 42. Thus, the X-axis direction position X1 at which the output of the contact detection means (AE sensor) 35 has changed is stored in the memory 42 as a reference position for starting truing of the arc grinding surface 21b of the grinding wheel 21. Thereafter, in step 130, the table 12 is moved (rightward) in the X-axis direction and positioned at the traverse start position (position indicated by the two-dot chain line in FIG. 4D), and then the program is returned to the grinding wheel 21. The truing cycle for truing the cylindrical grinding surface 21a is completed. Steps 124 to 128 described above constitute truing start reference position detection means in the claims.

  Subsequently, a truing cycle for truing the arc grinding surface 21b of the grinding wheel 21 shown in FIG. 6 is started. In the figure, first, in step 202, the table 12 is moved (leftward) in the X-axis direction by the X-axis servomotor 55 from the position indicated by the two-dot chain line in FIG. 21a is moved along the outer peripheral surface of the truing tool 32 with zero cutting. In step 204, it is determined whether or not the table 12 has reached the truing start position before the cutting amount ΔX from the X-axis direction position (truing start reference position of the arc grinding surface 21b) X1 stored in step 128 described above. If it has not been reached yet (when the determination result is N0), the process returns to step 202 and the X-axis servomotor 55 continues to move the table 12 in the X-axis direction.

  When the table 12 reaches the truing start position (X1-ΔX), the determination result in step 204 is YES, and in the subsequent step 206, the table 12 and the grinding wheel base are controlled by the two-axis simultaneous control of the X-axis and Z-axis servomotors 55 and 51. As shown by the solid line in FIG. 3D, the grinding wheel 21 is moved with respect to the truing tool 32 along the circular path of a predetermined radius, and the circular grinding surface 21b of the grinding wheel 21 is moved. Truing. The above-mentioned step 206 constitutes the synchronization control means in the claims.

  As a result, the grinding wheel 21 is moved relative to the truing tool 32 along the arc locus P1-P2 as shown in detail in FIG. 7, and the arc grinding surface 21b of the grinding wheel 21 has a predetermined cutting amount (FIG. 7 is shaded). Thereafter, in step 208, the table 12 and the grinding wheel base 20 are returned to the original positions, and the truing cycle of the grinding wheel 21 is completed.

  Thus, during truing of the cylindrical grinding surface 21a of the grinding wheel 21, the truing start reference position X1 of the arc grinding surface 21b of the grinding wheel 21 is detected based on the signal change of the contact detection means 35, and the detected truing start is performed. Since the table 12 and the grindstone table 20 are synchronously controlled in the X-axis direction and the Z-axis direction so as to give a predetermined cutting amount based on the reference position X1, the arc grinding surface 21b is trued. Regardless of the surface properties of the grinding surface 21b, the cutting start position of the arc grinding surface 21b can be determined accurately. As a result, the arc grinding surface can be trued with high accuracy in the minimum necessary truing cycle.

  In the above-described first embodiment, the cylindrical grinding surface 21a of the grinding wheel 21 is trued a predetermined number of times while sequentially providing incisions, but this is particularly a grinding stone made of superabrasive grains such as CBN. In the wheel 21, there is a restriction that the cutting amount of the truing tool 32 relative to the grinding wheel 21 cannot be increased, so that the cylindrical grinding surface 21 a of the grinding wheel 21 can be sharpened and shaped accurately. The number of times is not particularly limited. For example, when truing is performed in a state where the damage of the cylindrical grinding surface 21a of the grinding wheel 21 is small, the truing can be completed with one cut. On the other hand, the truing of the arc grinding surface 21b of the grinding wheel 21 is not completed by one cut as described in the embodiment, but may be performed in several steps.

  FIGS. 8 and 9 show a second embodiment of the present invention, in which in addition to the cylindrical grinding surface 21a and the arc grinding surface 21b of the grinding wheel 21, the end grinding surface 21c can also be trued. . That is, the grinding wheel 21 in the second embodiment has a cylindrical grinding surface 21a parallel to the movement direction (X-axis direction) of the table 12 on the outer peripheral surface, and the movement direction (Z-axis direction) of the grinding wheel base 20 on the end surface. ) And an end grinding surface 21c parallel to each other, and an arc grinding surface 21b having a predetermined radius is smoothly connected between one end of the cylindrical grinding surface 21a and the end grinding surface 21c.

  As shown in FIG. 8, the grinding wheel 21 traverses the cylindrical portion W1 of the workpiece W with the cylindrical grinding surface 21a, and simultaneously controls the arc corner W2 with the table 12 and the grinding wheel base 20 with the arc grinding surface 21b. Then, the end surface portion W3 of the workpiece W is ground by the end surface grinding surface 21c.

  On the other hand, the truing device 30 provided on the table 12 has a cylindrical grinding surface 21a of the grinding wheel 21 on the outer peripheral surface of a disk-shaped metal core attached to one end of the truer shaft 31, as shown in FIG. And a thin cylindrical first truing tool 32 for truing the arc grinding surface 21b, and a cup-shaped second truing tool for truing the end surface grinding surface 21c of the grinding wheel 21 on the end surface of the metal core. 33 is provided coaxially.

  In the second embodiment, the truing of the arc grinding surface 21b is completed after truing the cylindrical grinding surface 21a and the arc grinding surface 21b of the grinding wheel 21 in the same manner as described in the first embodiment. With reference to the X-axis direction position Z2 (see FIG. 9A), as shown in FIG. 9B, the end grinding surface 21c of the grinding wheel 21 is made to correspond to the end surface position of the second truing tool 33, In this state, the end grinding surface 21c of the grinding wheel 21 is trued by the second truing tool 33 by moving the grinding wheel base 20 back and forth by a predetermined amount in the Z-axis direction.

  In the above-described embodiment, the example in which the contact between the grinding wheel 21 and the truing tool 32 is detected by the AE sensor 35 has been described. However, the contact detection means is not particularly limited to the AE sensor, and the contact of various configurations. A detection means can be used.

  In the above-described embodiment, the example in which the truing device 30 is installed on the table 12 has been described. However, the truing device 30 is relatively movable in the X-axis direction and the Z-axis direction with respect to the grindstone table 20, for example, a spindle You may install in the base 13 or the tailstock 14.

  Furthermore, in the above-described embodiment, an example of truing the grinding wheel 21 having the arc grinding surface 21b at one end of the cylindrical grinding surface 21a has been described. For example, like a grinding wheel used for a crankpin grinding machine, FIG. 8 shows a cup-shaped truing tool for truing an end grinding surface when truing a grinding wheel having an arc grinding surface and end grinding surfaces connected to the arc grinding surface at both ends of the cylindrical grinding surface. This can be done by disposing the cup-shaped truing tool in the opposite direction.

  Note that the flowcharts shown in FIGS. 4 to 6 are merely examples suitable for carrying out the present invention, and the present invention is not limited to this, and the scope of the present invention is not deviated. Of course, various embodiments can be adopted.

It is a top view of the grinding machine provided with the truing apparatus which shows the 1st Embodiment of this invention. It is a figure which shows the process state of the workpiece | work with a grinding wheel. It is explanatory drawing explaining the truing operation | movement of the grinding wheel in FIG. It is a flowchart which shows the truing operation | movement by the numerical control apparatus which controls a grinding machine. It is a flowchart which shows the truing cycle of the cylindrical grinding surface in FIG. It is a flowchart which shows the truing cycle of the circular arc grinding surface in FIG. It is explanatory drawing explaining the truing operation | movement of a circular arc grinding surface. It is a process state figure of the workpiece | work by the grinding wheel which shows the 2nd Embodiment of this invention. It is explanatory drawing explaining the truing operation | movement of the grinding wheel in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Table, 13 ... Spindle head, 14 ... Tailstock, 20 ... Grinding wheel stand, 21 ... Grinding wheel, 21a ... Cylindrical grinding surface, 21b ... Arc grinding surface , 30 ... Trueing device, 31 ... Truer shaft, 32 ... Truing tool, 35 ... Contact detection means (AE sensor), 40 ... Numerical control device, 51 ... Z-axis servo motor 55 ... X-axis servo motor, 57 ... X-axis direction moving means, 58 ... Z-axis direction moving means, W ... workpiece, W1 ... cylindrical part, W2 ... arc corner part .

Claims (2)

In a truing apparatus for truing a grinding wheel having an arc grinding surface at least one end of a cylindrical grinding surface with a truing tool, an X-axis direction moving means for moving the truing tool relative to the grinding wheel in the rotational axis direction of the grinding wheel. Z-axis direction moving means for moving the truing tool relative to the grinding wheel in a direction intersecting the rotational axis direction of the grinding wheel; and contact detecting means for detecting contact between the truing tool and the grinding wheel; The circular grinding surface of the grinding wheel based on the signal change of the contact detection means when the cylindrical grinding surface of the grinding wheel is truing by the relative movement of the grinding wheel and the truing tool by the X-axis direction moving means. Truing start reference position detecting means for detecting a truing start reference position of the truing, and the truing start reference The X-axis direction moving means and the Z-axis direction moving means are synchronously controlled based on the truing start reference position detected by the quasi-position detecting means, and the synchronous control means for truing the arc grinding surface. A grinding wheel truing device. 2. The grinding wheel truing device according to claim 1, wherein the contact detection means includes an AE sensor that outputs an AE signal generated by contact between the truing tool and the grinding wheel.

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