JP2009196022A - Grinding method and grinding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently process a workpiece with a grinding tolerance which differs depending on a rotating angle while suppressing the occurrence of the vibration of a grinding wheel. <P>SOLUTION: An inner surface grinding machine comprises the grinding wheel 24, a wheel head 20 rotatingly driving the workpiece 1, a moving mechanism including a first table 26 which feeds the grinding wheel 24 and the peripheral surface of the workpiece in the cut-in direction relative to each other, and an NC device 30 for controlling the driving of the wheel head 20. The NC device 30 comprises: a contact detection part 32 for detecting the contact of the grinding wheel 24 on the inner peripheral surface of the workpiece based on the value of the motor power of a grinding wheel-driving motor which is output from a power detection circuit 21; and a speed control part 36 for outputting control signals to a workpiece-driving motor 14 to control the rotating speed of the workpiece 1 during the rotation based on the detection of the contact so that the rotational speed of the workpiece 1 (spindle 12) in such a state that the grinding wheel 24 and the inner peripheral surface of the workpiece are brought into contact with each other is lower than the rotational speed in other cases. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for grinding an inner peripheral surface or an outer peripheral surface of a workpiece.

  Generally known is a method of grinding a work peripheral surface into a predetermined shape such as a perfect circle or an ellipse by cutting and feeding the grindstone at a constant feed speed to the work peripheral surface while rotationally driving the grindstone and the work. ing.

  By the way, when grinding a workpiece with a different grinding allowance depending on the rotation angle of the workpiece by the above method, such as when the peripheral surface is uneven or misalignment occurs when the workpiece is mounted, Due to the intermittent contact with the surface, this causes the grindstone to vibrate and possibly damages the grindstone. Such a vibration of the grindstone greatly hinders improvement in processing accuracy.

Therefore, conventionally, as described in Patent Document 1, the grinding force of a workpiece by a grindstone is detected, and while the fluctuation range is larger than a specified value (that is, while the undulation of the workpiece circumferential surface is large), the workpiece is moved at a low speed. Drive, thereby suppressing the vibration of the grindstone and the like, and when the fluctuation range is equal to or less than the predetermined value (that is, when the work peripheral surface is in contact with the grindstone over almost the entire circumference), the rotation speed of the work can be increased. Has been done.
JP-A-4-322967

  However, in the method as described in Patent Document 1, for example, the grindstone is in contact with only a part of the peripheral surface of the work during one rotation of the work, and the most part is non-contact (air cut state). However, since the workpiece is uniformly driven at a low speed until the fluctuation range becomes equal to or less than the predetermined value, the workpiece is driven at a low speed for a relatively long time depending on the peripheral shape of the workpiece. Therefore, there is room for improvement in efficiently machining the inner peripheral surface of the workpiece.

  An object of this invention is to process more efficiently the workpiece | work which has the surrounding surface from which grinding allowance changes with rotation angles, suppressing generation | occurrence | production of the vibration of a grindstone, etc. in view of said situation.

  In order to solve the above-mentioned problems, the present invention rotates the workpiece having a circumferential surface having a grinding allowance different depending on the rotation angle, and relatively feeds the workpiece circumferential surface and the grindstone in the cutting direction, thereby the circumferential surface of the workpiece. Is a grinding method for processing a grinding wheel to detect a rotational load of the grindstone to detect a contact state between the grindstone and the work peripheral surface, and when the grindstone and the work peripheral surface are in a contact state. The rotation speed during one rotation of the workpiece is controlled so that the rotation speed of the workpiece is lower than the rotation speed in the non-contact state. More specifically, it includes an approach step in which the grindstone approaches the workpiece peripheral surface while rotating the workpiece at a predetermined approach speed, and a machining step after the point when the grindstone contacts the workpiece peripheral surface. In this processing step, when the grindstone and the workpiece peripheral surface are in contact, the workpiece is rotationally driven at a predetermined low speed slower than the approach speed, and when the grindstone and workpiece peripheral surface are in a non-contact state, The workpiece is rotationally driven at a predetermined high speed that is faster than the low speed.

  Thus, in the machining process, according to the method of switching the rotation speed of the workpiece during one rotation of the workpiece based on the detection of the contact state between the grindstone and the workpiece circumferential surface, the grinding wheel and the workpiece circumferential surface are rotated during one rotation of the workpiece. During the contact, the vibration of the grindstone can be suppressed by rotating the work at a low speed. When the grindstone and the work surface are not in contact with each other, the work is rotated at a high speed to reduce the air cut period. Time can be reduced. Therefore, compared to the conventional method, that is, the conventional method in which the workpiece is driven at a uniform low speed regardless of the contact between the grindstone and the workpiece peripheral surface, the workpiece circumference is efficiently suppressed while suppressing the occurrence of vibration of the grindstone. The surface can be processed.

  Even if the change of the contact state between the grindstone and the workpiece peripheral surface from the contact state to the non-contact state is detected and the rotation speed of the workpiece is controlled immediately, the workpiece is rotating slightly. Response delay can occur. For this reason, in the machining step, the rotation angle during one rotation of the workpiece is detected, and based on the detected angle and the detection of the contact state, the grinding stone and the workpiece peripheral surface change from a non-contact state to a contact state. The rotation angle is stored, and based on the stored rotation angle, the rotation angle of the workpiece during the next one rotation of the workpiece and the switching angle at which the rotation speed of the workpiece should be switched from the high speed to the low speed is determined. Based on the above, it is preferable to control the rotation speed of the workpiece during the next rotation of the workpiece.

  As described above, if the rotation speed during the next rotation of the workpiece is switched based on the contact state during the previous rotation of the workpiece, the response delay problem as described above can be solved.

  In this case, it is preferable to determine the switching angle so as to switch the rotation speed of the workpiece from the high speed to the low speed as early as a predetermined angle with respect to the rotation angle stored during the previous rotation of the workpiece. .

  That is, when there is a convex portion on the work peripheral surface, the contact range between the grindstone and the work peripheral surface is usually expanded as the cutting feed of the grindstone proceeds. Therefore, during the next rotation of the workpiece, if the rotation speed of the workpiece is switched from a high speed to a low speed by a predetermined angle earlier than the rotation angle stored during the previous rotation of the workpiece as described above, It is possible to more reliably switch the rotation speed of the workpiece when the grindstone contacts the peripheral surface.

  On the other hand, a grinding apparatus according to the present invention comprises a grindstone, a work drive means for rotationally driving a work, and a feed drive means for relatively feeding the grindstone and the work peripheral surface in the cutting direction, and has a non-circular circumference. Control means for controlling the drive means to process the peripheral surface of the workpiece having a surface into a perfect circle, the control means based on detection of a rotational load of the grindstone and the grindstone Based on the contact detection means for detecting the contact state with the work peripheral surface, and the contact state detection by the contact detection means, the rotational speed of the work when the grindstone and the work peripheral surface are in a contact state is a non-contact state. Speed control means for controlling the rotation speed during one rotation of the workpiece so as to be lower than the rotation speed at the time.

  In this grinding apparatus, when the grindstone and the workpiece circumferential surface are driven to be fed relative to each other in the cutting direction and the grindstone is in contact with the workpiece circumferential surface, the contact detection means detects the speed control based on this detection. The means controls the work drive means so that the work rotation speed when the grindstone and the work surface are in contact with each other is lower than the rotation speed at other times. Control the rotation speed. Therefore, according to this grinding apparatus, the grinding method according to claim 1 can be satisfactorily performed in the peripheral surface grinding of a workpiece having a grinding allowance different depending on the rotation angle.

  The speed control means determines the workpiece until the grindstone comes into contact with the work peripheral surface in response to detection of a contact state by the contact detection means associated with the relative feed of the grindstone and the work peripheral surface in the cutting direction. When the grindstone is in contact with the workpiece peripheral surface and the grindstone is in contact with the workpiece peripheral surface, the workpiece is rotationally driven at a predetermined low speed slower than the approach speed. When the grindstone and the workpiece peripheral surface are in a non-contact state, the workpiece is rotationally driven at a predetermined high speed higher than the low speed.

  According to this grinding apparatus, the grinding method according to claim 2 can be carried out satisfactorily.

  In this grinding apparatus, the grindstone and the work peripheral surface are not in contact with each other based on the angle detection means for detecting the rotation angle of the work during one rotation of the work, and the detection angle and detection of the contact state by the contact detection means. Storage means for storing the rotation angle of the workpiece when changing from the state to the contact state. During the next rotation of the workpiece, the rotation of the workpiece is performed based on the rotation angle stored during the previous rotation of the workpiece. The speed control means is configured to switch the speed from the high speed to the low speed.

  In this grinding apparatus, when the detection state by the contact detection unit changes from the non-contact state to the contact state, the rotation angle of the workpiece at that time is stored in the storage unit. Then, the speed control means switches the speed from the high speed to the low speed during the next rotation of the workpiece 1 based on the rotation angle during the previous rotation of the workpiece stored in the storage means. Therefore, according to this grinding apparatus, the grinding method according to claim 3 can be carried out satisfactorily.

  In this apparatus, the recording speed control means, during the next rotation of the workpiece, sets the rotation speed of the workpiece from the high speed earlier by a predetermined angle with respect to the rotation angle stored during the previous rotation of the workpiece. You may switch to low speed.

  According to this grinding apparatus, the grinding method according to claim 4 can be carried out satisfactorily.

  The present invention provides a grinding method in which the peripheral surface of a workpiece having a peripheral surface with a grinding allowance that varies depending on a rotation angle is processed into a predetermined shape. Since the rotation speed during one rotation of the workpiece is controlled so as to be lower than the rotation speed at other times, the workpiece peripheral surface is processed more efficiently while effectively suppressing the occurrence of vibration of the grindstone. can do.

  A preferred embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to the internal grinding for grinding the inner peripheral surface of the cylindrical workpiece 1, but the present invention is also applicable to the cylindrical grinding for grinding the outer peripheral surface of the workpiece. Is possible.

  FIG. 1 schematically shows an internal grinding machine, which is a grinding apparatus according to the present invention, in a plan view. The internal grinding machine shown in this figure includes a work support head 10 for supporting the work 1 and a wheel head 20 having a grinding wheel 24 on its base.

  The workpiece support head 10 is provided with a spindle 12 having a chuck for holding (fixing) the workpiece 1. The main shaft 12 is connected to a driving mechanism (not shown) having a work driving motor 14 as a driving source (corresponding to the work driving means according to the present invention), and is attached to the work supporting head 10 integrally with the work 1 held by the chuck. On the other hand, it is driven to rotate.

  The wheel head 20 is disposed so as to face the workpiece support head 10 in the axial direction of the main shaft 12.

  A grindstone shaft 22 is attached to the wheel head 20, and a grindstone 24 is fixed to the tip of the grindstone shaft 22. The grindstone 24 is a flat grindstone wheel having a straight grindstone surface along the axial direction, for example. The wheel head 20 incorporates a grindstone driving motor (not shown) that rotates the grindstone shaft 22 and the grindstone 24 at high speed.

  The wheel head 20 is provided so as to be movable in a direction parallel to the grindstone shaft 22 and a cutting direction (vertical direction in FIG. 1) perpendicular to the wheel head 20 on a horizontal plane. Specifically, on the base, there is a movement having a first table 26 movable in a direction parallel to the grindstone shaft 22 and a second table 28 provided on the first table and movable in the cutting direction. A mechanism is provided, and the wheel head 20 is supported on the second table 28 of the moving mechanism. That is, the grindstone shaft 22 and the grindstone 24 are rotationally driven at a high speed, the grindstone 24 is inserted into the workpiece 1 in the rotationally driven state, and the grindstone 24 is cut and fed in the radial direction of the workpiece 1 together with the wheel head 20. Thus, the grindstone 24 is pressed against the inner peripheral surface of the workpiece to grind the inner peripheral surface. In the present invention, the workpiece support head 10 may be moved instead of the grindstone 24 to feed in the cutting direction.

  The wheel head 20 is connected to a power detection circuit 21 that detects a value corresponding to the motor power (grinding power) of the grindstone driving motor, that is, the rotational driving torque (rotational load) of the grindstone 24. The detection signal of the power detection circuit 21 is input to the NC device 30.

  The NC device 30 (corresponding to the control means according to the present invention) comprehensively controls the operations of the workpiece support head 10 and the wheel head 20 so as to execute a predetermined grinding operation according to a program stored in advance. It includes functional configurations such as a contact detection unit 32, a storage unit 34, and a speed control unit 36.

  The contact detection unit 32 corresponds to a contact detection unit according to the present invention. The contact detection unit 32 detects the contact of the grindstone 24 with the inner peripheral surface of the workpiece 1 based on the detection signal (grinding power detection signal) input from the power detection circuit 21 and is built in the workpiece drive motor 14. Based on a signal input from an unillustrated encoder (corresponding to the angle detection means according to the present invention), the rotation angle of the workpiece 1 at which the grindstone 24 starts to contact is stored in the storage unit 34. Specifically, the storage unit 34 has a storage area corresponding to one rotation of the workpiece at every predetermined angle, and the contact detection unit 32 detects that the grindstone 24 has come into contact with the inner peripheral surface of the workpiece. Then, contact information (hereinafter referred to as contact recording) is stored in a recording area corresponding to the rotation angle of the workpiece 1 at that time. In that case, when contact is detected intermittently a plurality of times during one rotation of the workpiece, the contact detection unit 32 stores the contact record in the storage area for each rotation angle.

  The speed control unit 36 corresponds to a speed control unit according to the present invention. The speed control unit 36 controls the rotational speed of the work drive motor 14 by outputting a control signal to the work drive motor 14, and drives the work drive motor 14 at a preset speed. Based on the contact record stored in the storage unit 34, the rotation speed of the work drive motor 14 is switched and controlled.

  Next, control of the machining operation by the NC device 30 will be described with reference to the flowchart of FIG. Note that the machining operation shown in this embodiment is, for example, an outer ring of a wind power generation bearing or the like, and has a convex portion 1a or the like as shown in FIG. 1 is a premise that the inner peripheral surface of the workpiece 1 is processed into a perfect circle having a predetermined inner diameter (indicated by reference numeral 2).

  First, the NC device 30 clears the data in the storage unit 34, and then moves the first and second tables 26 and 28, whereby the grindstone 24 is placed between the inner peripheral surface of the work 1 and a predetermined amount. Is inserted into the workpiece 1 at a position where a gap is left (indexing of the grindstone 24 into the workpiece 1 is performed), and the grindstone drive motor built in the wheel head 20 is operated to grindstone shaft 22 and grindstone 24 is integrally rotated at high speed (steps S1, S3).

In this state, the speed control unit 36 outputs a control signal to the work drive motor 14 to rotate and drive the spindle 12 and the work 1 together, and supply of the machining fluid to the work 1 by a supply means (not shown) is started. Further, the value of the detection signal output from the power detection circuit 21 is stored in the contact detection unit 32 (step S5). That is, the contact detection unit 32 stores the value W ₀ of the grinding power of the unloaded condition _(see Figure 3).

Next, the NC device 30 increases the rotational speed of the spindle 12 to a preset speed V ₁ (corresponding to the approach speed according to the present invention), and then drives the second table 28 to cut the grindstone 24. Feeding is started (steps S7 and S9).

  When the cutting feed is started, the speed control unit 36 adds +5 to the current rotation angle of the main spindle 12 based on the input signal from the encoder built in the work drive motor 14 and the data in the storage unit 34. It is determined whether or not there is a contact record memorized during the previous rotation of the workpiece at the position of ° (step S11).

Here, when it is determined NO, whether or not the grindstone 24 has contacted the inner peripheral surface of the workpiece (hereinafter referred to as contact detection) in the contact detection unit 32, that is, the grindstone 24 has contacted the convex portion 1 a of the workpiece 1. It is determined whether or not it has been done (step S13). This determination is made by comparing the detection signal value output from the power detection circuit 21 with a preset threshold value Wt (see FIG. 3;> W ₀ ). That is, when the grindstone 24 comes into contact with the work inner peripheral surface, the rotational load of the grindstone 24 increases and the grinding power rises. Therefore, the contact detection unit 32 detects the threshold value Wt set in advance and the detection from the power detection circuit 21. The signal value is compared, and contact is detected when the signal value exceeds the threshold value Wt.

If the determination in step S13 is no, the process proceeds to step S7. On the other hand, when the determination in step S13 is YES, the NC device 30 causes the spindle at the time when the value of the detection signal output from the power detection circuit 21 exceeds the threshold value Wt by the contact detection unit 32. 12 (work 1) is stored in the storage unit 34, and further, a control signal is output from the speed control unit 36 to the work drive motor 14, whereby the rotation speed of the spindle 12 is set to a preset speed V ₂ ( <V ₁ ; see FIG. 3; predetermined low speed according to the present invention) (steps S15 and S17).

Then, it is determined whether the value of the detection signal output from the power detection circuit 21 in the contact detection unit 32 is lower than the threshold value Wt, that is, whether the grindstone 24 is not in contact with the work inner peripheral surface (step S19). , when the result of the determination is YES, NC device 30, the process proceeds to step S7, by outputting a control signal to the workpiece drive motor 14 from the speed controller 36, the speed V ₂ of the rotational speed of the spindle 12 To the speed V ₁ (corresponding to a predetermined high speed according to the present invention).

On the other hand, if the determination in step S19 is NO, the NC device 30 indicates that the value of the detection signal output from the power detection circuit 21 is continuously the threshold value Wt in one rotation of the spindle 12 (work 1). Is determined (step S21). That is, it is determined whether the inner peripheral surface of the workpiece has contacted the grindstone over almost the entire circumference. And when judgment of step S21 is NO, it transfers to step S17. On the other hand, if the determination in step S21 is YES, the NC device 30 causes the work drive motor 14 to output a control signal from the speed control unit 36, so that the spindle 12 according to the cutting feed amount of the grindstone 24. Are sequentially switched from a preset rotation speed V ₃ (V ₃ <V ₂ ) to V ₄ (V ₄ <V ₃ ), whereby the inner circumference of the workpiece 1 processed into a substantially perfect circle. The surface is sequentially subjected to roughing, finishing, and spark-out processing (steps S23 to S27), and when the spark-out processing is completed, the NC device 30 drives the first and second tables 26 and 28. Then, the grindstone 24 is pulled out from the work 1. Thereby, a series of internal grinding of the workpiece 1 is completed.

In the above control, when the determination in step S11 is YES, NC device 30, by the speed control unit 36 to output a control signal to the workpiece drive motor 14, the rotational speed of the spindle 12 to the speed V ₂ Switching (step S29). Then, after waiting for the value of the detection signal output from the power detection circuit 21 to exceed the threshold Wt (step S31), when the value of the detection signal exceeds the threshold Wt (YES in step S31), the NC device 30 Is stored in the storage unit 34 by the contact detection unit 32 at that time, that is, when the value of the detection signal output from the power detection circuit 21 exceeds the threshold value Wt (step S33). Control goes to step S19.

  The operation of the spindle 12 (work 1) based on the control of the NC device 30 as described above will be described with reference to FIG. FIG. 3 shows a correspondence between the grinding power value (detection signal value output from the power detection circuit 21) for one rotation of the main shaft 12 (work 1) and the rotational speed of the main shaft 12.

Under the control of the NC device 30, the feed of the grindstone 24 is started, and the spindle 12 is driven at a high speed V ₁ until the grindstone 24 comes into contact with the inner peripheral surface of the workpiece. When the cutting feed of the grindstone 24 advances, the grindstone 24 comes into contact with the work inner peripheral surface (convex portion 1a), and the grinding power value exceeds the threshold value Wt as shown by the solid line in the figure, the rotational speed of the spindle 12 is accordingly increased. It is switched from the velocity _{V 1} to velocity _{V 2.} Further, the rotation angle (angle θ1) of the main shaft 12 at that time is stored in the storage unit 34. In this embodiment, the time before the grinding power 24 exceeds the threshold value Wt for the first time when the grindstone 24 contacts the workpiece inner peripheral surface corresponds to the approach process of the present invention, and the time after that time is the machining process. is there.

Then, when the spindle 12 further rotates and the grindstone 24 is detached from the work inner peripheral surface (convex portion 1a) and the grinding power value becomes less than the threshold value Wt (angle θ2), the rotational speed of the spindle 12 is accordingly increased to the speed V. switch to _2, et al speed _{V 1.} That is, during one rotation of the spindle 12, while the grinding wheel 24 and the workpiece in the peripheral surface is in contact is a low speed drive spindle 12 at a rate V _2, between the other non-contact spindle 12 at a rate V ₁ Driven at high speed.

When the grindstone 24 first contacts the workpiece inner peripheral surface is the nth rotation, the next workpiece rotation (n + 1th rotation) is indicated by a broken line in FIG. 3 based on the data in the storage unit 34. as such, the previous (n-th rotation), the speed V ₁ rotation speed of the spindle 12 just 5 ° than the rotational angle of the workpiece 1, the grinding wheel 24 starts to contact early (θ1-5 °) the speed V ₂ After that, when the grinding power value becomes less than the threshold value Wt (angle θ2 ′), the rotational speed of the spindle 12 is switched from the speed V _{2 to the} speed V _{1 accordingly} . In this case as well, when the grinding power value exceeds the threshold value Wt, the rotation angle (angle θ1 ′) of the main shaft 12 at that time is stored in the storage unit 34.

After the n + 2nd rotation, the rotation speed of the spindle 12 is switched based on the data in the storage unit 34 and the data in the storage unit 34 is updated so that the work 1 is rotating once, as in the n + 1th rotation. When the storage unit 34 is no longer updated, the rotational speed of the spindle 12 is sequentially switched from V _{3 to} V ₄ as described above.

As described above, in the internal grinding machine according to the present invention (the grinding method according to the present invention), the rotational speed during one rotation of the main shaft 12 (work 1) is used to detect contact between the grindstone 24 and the work inner peripheral surface. based switched, at the time of non-contact, while high-speed driving of the spindle 12 (the workpiece 1) at a speed V _1, at the time of contact, driving at a low speed by the spindle 12 (the workpiece 1) slow speed V ₂ than the speed V ₁ of the. Therefore, during the contact between the grindstone 24 and the work inner peripheral surface, it is possible to suppress the vibration of the grindstone 24 by rotating the work 1 at a low speed. In the contact state, the so-called air cut period can be shortened by rotating the workpiece 1 at a high speed. For example, FIG. 5 schematically shows the rotational speed of each rotation of the spindle 12 (work 1) from the start of cutting feed to rough machining when the work 1 shown in FIG. 4 is ground by the internal grinding machine. It is shown in. In this figure, the thin line indicates the range in which a high speed drive spindle 12 at a speed V _1, a thick line indicates the range of low speed driving at a speed V _2. According to the conventional grinding process, in order to suppress the vibration of the grindstone and the like, the spindle (workpiece) was uniformly driven at a low speed from the start of the cutting feed to the roughing process. As shown in the figure, the spindle 12 (work 1) is driven at a high speed in a large range from the start of cutting feed to rough machining.

  Therefore, according to the above-mentioned internal grinding machine, in the grinding of the workpiece 1 having the peripheral surface whose grinding allowance varies depending on the rotation angle, the generation of vibrations of the grindstone 24 and the like are suppressed, but the efficiency is higher than that of the conventional method. It is possible to machine the inner peripheral surface of the workpiece 1 well.

In particular, as described above, in this inner surface grinding machine, a contact record between the grindstone 24 and the work inner peripheral surface in one rotation of the main spindle 12 (work 1) is stored in an updated manner, and the grindstone 24 is temporarily stored in the work piece. After contact with the peripheral surface, the rotational speed of the main shaft 12 is switched from the speed V ₁ to the speed V ₂ at a timing earlier by a certain rotation angle (5 ° in the embodiment) based on the contact record. Therefore, this has the advantage that the problem of response delay can be solved. That is, until the rough grinding process, the rotational speed of the spindle 12 (work 1) may be switched based on the contact detection between the grindstone 24 and the work inner peripheral surface. It is conceivable that the work inner peripheral surface (convex portion 1a) and the grindstone 24 come into contact with each other at a high speed due to a response delay until the speed switching is completed, and the grindstone 24 is damaged, for example. However, when the rotational speed of the spindle 12 is switched at a timing earlier by a certain rotational angle based on the contact record stored during the previous work rotation as described above, the point at which the grindstone 24 actually contacts the work inner peripheral surface. in order to be able to switch the rotational speed of the spindle 12 (the workpiece 1) in advance from the speed V ₁ to velocity V _2, it is possible to solve the problem of response delay as described above. In this internal grinding machine, a response delay may occur at the initial contact of the grindstone 24 with the work inner peripheral surface. At such an initial stage of contact, the contact area between the grindstone 24 and the work inner peripheral surface is compared. Therefore, there is almost no inconvenience that the grindstone 24 is damaged.

  The internal grinding machine according to the present invention (the grinding method according to the present invention) has been described above. However, the internal grinding machine (grinding method) is an example of a preferred embodiment of the present invention, and its specific configuration (grinding) The processing method) can be changed as appropriate without departing from the scope of the present invention.

  For example, in the above embodiment, the power value of the grindstone driving motor is detected as the rotational load of the grindstone 24. However, for example, the current value supplied to the motor may be detected.

Moreover, in the said embodiment, the grindstone 24 is made to approach with respect to a workpiece | work internal peripheral surface, while rotating the workpiece | work 1 (approach process), and the grindstone 24 is made to contact a work internal peripheral surface, and processing is started. (Machining process), the rotational speed (V ₁ ) of the work 1 (spindle 12) when the grindstone 24 and the work inner peripheral surface are not in contact with each other in the machining process, and the rotational speed of the work 1 (spindle 12) in the approach process. Although it is set to the same speed as (V ₁ ), of course, it does not need to be the same speed. In short, in the machining process, if the rotational speed of the workpiece 1 when the grindstone 24 and the inner peripheral surface of the workpiece are in contact with each other is lower than the rotational speed in the non-contact state, the specific speed is It can be set as appropriate.

In the embodiment, the rotation speed of the work 1 is changed from the speed V ₁ to the speed V ₂ at an early stage by a predetermined angle (5 °) with respect to the rotation angle (contact recording) stored during one rotation of the previous work 1. The next rotation speed switching angle is determined so as to be switched, but of course, the contact recording may be switched earlier by an angle of more than 5 ° or an angle of less than 5 °. In short, how early the rotation speed of the workpiece 1 is switched with respect to the contact recording can be appropriately changed according to the specific shape of the workpiece 1 or the like.

  In the embodiment, the example in which the workpiece peripheral surface is ground into a perfect circle has been described. However, the shape of the peripheral surface is not limited to a perfect circle, and may be a non-circular shape such as an ellipse. In short, the present invention can be applied to grinding of a workpiece peripheral surface having a different grinding allowance depending on the rotation angle.

It is the schematic which shows the internal grinding machine which concerns on this invention, and its control system. It is a flowchart which shows an example of control of the process operation by NC apparatus. It is a figure for demonstrating operation | movement of the spindle (workpiece | work) based on control of NC apparatus. It is a plane schematic diagram showing an example of a work. It is the schematic which shows the rotational speed for every rotation of the main axis | shaft (workpiece | work) from a cutting feed start to roughing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Work 10 Work support head 12 Main shaft 14 Work drive motor 20 Wheel head 22 Grinding wheel shaft 24 Grinding wheel 26 First table 28 Second table 30 NC device 32 Contact detection part 34 Storage part 36 Speed control part

Claims (8)

This is a grinding method in which a workpiece having a peripheral surface with different grinding allowance is rotated according to the rotation angle, and the peripheral surface of the workpiece and the grindstone are relatively fed in the cutting direction to process the peripheral surface of the workpiece into a predetermined shape. And
By detecting the rotational load of the grindstone, the contact state between the grindstone and the work surface is detected, and the work speed when the grindstone and the work surface are in contact is the rotation speed when the work is in a non-contact state. A grinding method characterized in that the rotational speed during one rotation of the workpiece is controlled so as to be lower than that. In the grinding method according to claim 1,
An approach step of causing the grindstone to approach the workpiece peripheral surface while rotating the workpiece at a predetermined approach speed, and a processing step after the point when the grindstone contacts the workpiece peripheral surface,
In this processing step, when the grindstone and the workpiece peripheral surface are in contact, the workpiece is rotationally driven at a predetermined low speed slower than the approach speed, and when the grindstone and the workpiece peripheral surface are in a non-contact state, A grinding method characterized by rotating the workpiece at a predetermined high speed faster than a low speed. In the grinding method according to claim 2,
In the machining step, the rotation angle during rotation of the workpiece 1 is detected, and the rotation angle of the workpiece when the grindstone and the workpiece circumferential surface change from the non-contact state to the contact state based on the detected angle and the detection of the contact state. Based on the stored rotation angle, a rotation angle of the workpiece during the next rotation of the workpiece, and a switching angle at which the rotation speed of the workpiece should be switched from the high speed to the low speed is determined. A grinding method characterized by controlling the rotation speed of the workpiece during the next rotation of the workpiece. In the grinding method according to claim 3,
A grinding method characterized in that the switching angle is determined so that the rotation speed of the workpiece is switched from the high speed to the low speed as early as a predetermined angle with respect to the rotation angle stored during the previous rotation of the workpiece. The peripheral surface of a work having a grindstone, a work drive means for rotationally driving the work, and a feed drive means for relatively feeding the grindstone and the work peripheral surface in the cutting direction, and having a peripheral surface whose grinding allowance varies depending on the rotation angle. And a control means for controlling the drive means to process the shape into a predetermined shape,
The control means is a contact detection means for detecting a contact state between the grindstone and a work peripheral surface based on detection of a rotational load of the grindstone,
Based on the detection of the contact state by the contact detection means, the work rotates once so that the rotational speed of the work when the grindstone and the work peripheral surface are in contact is lower than the rotational speed when in the non-contact state. And a speed control means for controlling the rotational speed of the grinding device. In the grinding device according to claim 5,
The speed control means is configured to move the work to a predetermined approach until the grindstone comes into contact with the work peripheral surface in response to detection of a contact state by the contact detection means associated with relative feeding of the grindstone and the work peripheral surface in the cutting direction. When the grindstone is in contact with the workpiece peripheral surface and the grindstone is in contact with the workpiece peripheral surface, the workpiece is rotationally driven at a predetermined low speed slower than the approach speed, When the workpiece peripheral surface is in a non-contact state, the workpiece is rotated at a predetermined high speed faster than the low speed. The grinding apparatus according to claim 6, wherein
Angle detection means for detecting the rotation angle of the workpiece during one rotation of the workpiece;
Storage means for storing the rotation angle of the workpiece when the grindstone and the workpiece peripheral surface change from the non-contact state to the contact state based on the detection angle and detection of the contact state by the contact detection unit,
The speed control means switches the rotation speed of the workpiece from the high speed to the low speed based on the rotation angle stored during the previous rotation of the workpiece during the next rotation of the workpiece. apparatus. The grinding apparatus according to claim 7,
The speed control means switches the rotation speed of the workpiece from the high speed to the low speed at an early stage by a predetermined angle with respect to the rotation angle stored during the previous rotation of the workpiece during the next rotation of the workpiece. A characteristic grinding device.

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