JP2012030322A - Grinding device and grinding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding device capable of carrying out grinding work from mill scale grinding to finish grinding to a material to be worked at a lower cost without replacing a grindstone, and also to provide a grinding method.SOLUTION: The grinding device includes a support plate to which the material to be worked is mounted and a rotor in which the grindstone rotatable at a surface almost parallel to the support plate is arranged. The mill scale grinding is carried out while the spindle rotation number of the rotor is reduced, whether or not the mill scale grinding is completed is detected based on the fluctuation of a load current value, and the spindle rotation number of the rotor is increased at a time point when the mill scale grinding is completed.

Description

  The present invention relates to a grinding apparatus and a grinding method for grinding a surface of a general steel material, and in particular, grinding that can be performed from black skin grinding to finish grinding on a workpiece with a black skin without changing a grindstone. The present invention relates to an apparatus and a grinding method.

  When processing products from materials with black skin typified by metal materials, especially steel materials, first processing the black skin part of the surface, then executing normal material processing such as rough grinding, finish grinding, etc. . For example, when a black skin portion is processed by grinding, the type of grinding stone is generally different between the step of grinding the black skin and the step of grinding the material after removal of the black skin. For the purpose of reducing man-hours, the milling machine is used to process the black skin, and the grinding machine is used to process the material.

  Also disclosed is a method of performing the process of grinding the black skin and the process of processing the material with one machine by changing the processing speed between the first time and the second time. For example, in Patent Document 1, in the process of grinding the black skin for the first time, the processing speed is reduced by reducing the processing speed, and in the process of processing the material for the second time, the processing speed is based on the processing speed. A method for processing a material with a black skin that is processed back to the surface is disclosed.

JP-A-4-057653

  However, exchanging the type of grinding wheel during grinding is a cumbersome operation, and the grinding process must be stopped once, which may increase the number of work steps. . In addition, even if it is possible to reduce the number of man-hours by implementing a milling machine for the black skin process and a grinding machine for the raw material process, it requires multiple machines. There was a problem that the fixed cost was increased and it was difficult to reduce the manufacturing cost as a whole.

  On the other hand, in the method disclosed in Patent Document 1, although it is possible to grind the black skin with one machine, it requires two steps of grinding the black skin and processing the material. However, it is still difficult to reduce the time required for processing.

  The present invention has been made in view of such circumstances, and a grinding apparatus and a grinding method that can be performed at low cost from black skin grinding to finish grinding on a workpiece without exchanging a grindstone. The purpose is to provide.

  In order to achieve the above object, a grinding apparatus according to a first aspect of the present invention is a rotating body in which a support plate on which a workpiece is placed and a grindstone capable of rotating on a surface substantially parallel to the support plate are arranged. And a motor for rotationally driving the rotating body, wherein the rotational speed of the rotating body is changed during grinding of the surface of the workpiece by the grindstone.

  The grinding device according to a second aspect of the present invention is the grinding apparatus according to the first aspect, further comprising a current value detection means for detecting a current value of the motor, wherein the current value detected by the current value detection means is less than a predetermined value for a predetermined time. The rotation speed of the rotating body is changed at the subsequent time.

  A grinding device according to a third aspect of the present invention includes the control device for controlling the rotational speed of the spindle of the motor according to the second aspect, wherein the control device has a current value detected by the current value detecting means smaller than a predetermined value. Control is performed to increase the spindle speed of the motor when it is determined that the state has continued for a predetermined time.

  A grinding apparatus according to a fourth aspect of the present invention is the grinding apparatus according to any one of the first to third aspects, further comprising: another motor that rotationally drives the support plate on a surface substantially parallel to the rotating body. While the surface of the workpiece is ground by a grindstone, the rotational speed of the rotating body is changed and the rotational speed of the support plate is changed.

  The grinding device according to a fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, an annular grindstone is disposed on the rotating body.

  The grinding device according to a sixth aspect of the present invention is characterized in that, in any one of the first to fourth aspects of the invention, the rotating body has a plurality of grindstones arranged at a peripheral edge.

  The grinding device according to a seventh aspect is characterized in that, in the sixth aspect, the plurality of grindstones include grindstones having different coupling degrees.

  Next, in order to achieve the above object, a grinding method according to an eighth aspect of the present invention includes a rotating body on which a grindstone capable of rotating on a surface substantially parallel to a support plate on which a workpiece is placed is disposed. In a grinding method that can be executed by a grinding device in which the rotating body is rotationally driven by a motor, the rotational speed of the rotating body is changed during grinding of the surface of the workpiece by the grindstone. To do.

  A grinding method according to a ninth invention is the grinding method according to the eighth invention, wherein the current value of the motor is detected, and the rotational speed of the rotating body is changed when the detected current value is smaller than a predetermined value for a predetermined time. It is characterized by that.

  The grinding method according to a tenth aspect of the present invention is the grinding method according to the ninth aspect, wherein the control device for controlling the rotational speed of the spindle of the motor determines that the detected current value is smaller than a predetermined value for a predetermined time. It is characterized in that the main shaft rotational speed is increased.

  The grinding method according to an eleventh aspect of the present invention is the grinding method according to any one of the eighth to tenth aspects, wherein the support plate is rotationally driven on a surface substantially parallel to the rotating body by another motor, and the grinding stone is used. During the grinding of the surface of the workpiece, the rotational speed of the rotating body is changed and the rotational speed of the support plate is changed.

  In the first invention or the eighth invention, the rotational speed of the rotating body on which the grindstone is arranged can be changed during the grinding process. For example, in the grinding process of the black skin, by reducing the rotational speed of the rotating body, By applying the grinding wheel's cutting edge to the surface of the work piece with a low grinding force and increasing the number of revolutions of the rotating body when grinding of the black skin is completed, the cutting edge of the grinding wheel is raised on the surface of the work piece. It can be applied by grinding force. Therefore, it is possible to perform finish grinding after removing the black skin without stopping the grinding process in one grinding process, and it is possible to perform finish grinding without exchanging the grindstone.

  In the second or ninth invention, the current value of the motor is detected, and the rotational speed of the rotating body is changed when the detected current value is smaller than a predetermined value for a predetermined time. When the grinding of the black skin proceeds to a certain extent, the grinding resistance between the grindstone and the surface of the work piece decreases, and the current value becomes smaller as the load on the motor decreases. Therefore, it can be determined that the grinding of the black skin has been completed when the current value becomes smaller than the predetermined value, and it is possible to shift to finish grinding without changing the grindstone by increasing the number of revolutions of the rotating body. it can.

  In the third invention or the tenth invention, whether or not the grinding of the black skin is completed is controlled by increasing the spindle speed of the motor when the detected current value is smaller than the predetermined value for a predetermined time. Judgment can be made based on whether or not the current value has become smaller than the specified value. By increasing the spindle speed of the motor, the rotational speed of the rotating body can be increased, and the process can proceed to finish grinding without stopping the grinding process. Can do.

  In the fourth invention or the eleventh invention, the support plate is driven to rotate in a plane substantially parallel to the rotating body by another motor, and the rotational speed of the rotating body is changed during grinding of the surface of the workpiece by the grindstone. Change the rotation speed of the support plate. As a result, the relative rotational speed between the grindstone and the workpiece can be changed during the grinding process. For example, by reducing the rotational speed of the rotating body in the grinding process of the black skin, Is applied to the surface of the work piece with a low grinding force, and when grinding of the black skin is completed, the rotational speed of the rotating body is increased so that the cutting edge of the grindstone is applied to the surface of the work piece with a high grinding force. Can act. Therefore, it is possible to perform finish grinding after removing the black skin without stopping the grinding process in one grinding process, and it is possible to perform finish grinding without exchanging the grindstone.

  In the fifth invention, since the rotating body is provided with one annular grindstone, it is easy to replace the grindstone.

  In the sixth aspect of the invention, since the rotating body has a plurality of grindstones arranged at the periphery, it can be executed up to finish grinding without exchanging the grindstone, and only the necessary grindstone is exchanged according to the state of the grindstone. It becomes possible to do.

  In the seventh invention, since the plurality of grindstones include grindstones having different degrees of bonding, grinding resistance and grinding heat can be suppressed. Therefore, the sharpness of the grindstone can be increased by adjusting to an appropriate grinding resistance, and the grinding efficiency and the grinding accuracy can be improved.

  With the above configuration, the rotational speed of the rotating body on which the grindstone is arranged can be changed during the grinding process. For example, in the grinding process of the black skin, the rotational speed of the rotating body is reduced to reduce the cutting edge of the grindstone. By applying a low grinding force to the surface of the work piece and increasing the number of rotations of the rotating body when the black skin grinding is completed, the grinding stone cutting edge acts on the surface of the work piece with a high grinding force. Can be made. Therefore, it is possible to perform finish grinding after removing the black skin without stopping the grinding process in one grinding process, and it is possible to perform finish grinding without exchanging the grindstone.

It is a mimetic diagram showing an outline composition of a grinding device concerning an embodiment of the invention. It is the bottom view and side view of the rotary body of the grinding device concerning an embodiment of the invention. It is an illustration figure which shows the structure of the rotation control system of the motor which rotationally drives the rotary body of the grinding apparatus which concerns on embodiment of this invention. It is a graph which shows typically the time series fluctuation of the current value detected with the current detector of the grinding device concerning an embodiment of the invention. It is a flowchart which shows the procedure of the spindle speed change process of the control apparatus of the grinding device which concerns on embodiment of this invention. It is a bottom view of the other rotary body of the grinding device concerning an embodiment of the invention. It is a bottom view of the other rotary body of the grinding device concerning an embodiment of the invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a schematic diagram showing a schematic configuration of a grinding apparatus according to an embodiment of the present invention. As shown in FIG. 1, the grinding apparatus according to the present embodiment includes a support base 12 on which a workpiece is placed on the upper surface of a main body 11, and performs a surface grinding process on the support base 12. A workpiece to be processed, such as a steel material with a black skin, is placed.

  The support base 12 has a cylindrical plate shape and can be rotated in a substantially horizontal direction with the center of the circle as a rotation axis. Thereby, the grinding process can be performed evenly on the surface of the workpiece placed on the support base 12 with the grindstones 14, 14,. The support 12 uses the motor 22 as a drive source, and the spindle speed of the motor 22 is controlled by an instruction signal from the control device 17.

  The rotating body 13 has a cylindrical shape or a columnar shape, and a plurality of exchangeable grindstones 14, 14,... Are arranged on the peripheral portion of the surface on the support base 12 side. The rotating body 13 uses the motor 15 as a drive source, and the spindle speed of the motor 15 is controlled by an instruction signal from the control device 17. By appropriately controlling the spindle rotational speeds of the motor 22 and the motor 15, the relative rotational speed of the rotating body 13 and the support base 12 can be changed during the grinding process.

  Further, by adopting a configuration capable of sliding up and down with the rotating body support portion 16, the position of the rotating body 13 in the height direction can be changed. The method of changing the position of the rotary body 13 in the height direction may be performed manually by a lever or automatically by a motor for vertical movement.

  The plurality of grindstones 14, 14,... Are arranged at equal intervals on the peripheral edge of the surface of the rotating body 13 on the support base 12 side. FIG. 2 is a bottom view and a side view of the rotating body 13 of the grinding apparatus according to the embodiment of the present invention. FIG. 2A is a bottom view of the rotator 13 of the grinding apparatus according to the embodiment of the present invention, and FIG. 2B is a side view of the rotator 13 of the grinding apparatus according to the embodiment of the present invention. FIG.

  As shown in FIG. 2A, the plurality of grindstones 14, 14,... Having a substantially triangular cross-sectional shape are arranged at equal intervals on the peripheral edge of one surface of the rotating body 13, and the grindstone The two grindstones 14, 14 are joined to the rotating body 13 by the fixing members 20, 20,. The grindstone used in this embodiment is PA36L7V manufactured by Noritake, and in the example of FIG. 2A, 12 grindstones 14, 14,... Are arranged at equal intervals. The number of grindstones is not limited to twelve, and may be eight or six as long as the surface of the workpiece can be evenly ground.

  2 (a) and 2 (b), the outer peripheral surface of the rotating body 13 is connected between the ends of the two grindstones 14 and 14, and the grindstones 14 and 14 are connected to the outer periphery of the rotating body 13. The grindstone fixing member 20, 20, ... which fixes to a surface is provided. The grindstones 14, 14,... Are fixed to the outer peripheral surface of the rotating body 13 by the grindstone fixing members 20, 20,.

  Returning to FIG. 1, the control device 17 instructs the rotation speed of the motor 15 as the start and stop of the motor 15 and the spindle rotation speed. FIG. 3 is an exemplary diagram showing a configuration of a rotation control system of the motor 15 that rotationally drives the rotating body 13 of the grinding apparatus according to the embodiment of the present invention.

  As shown in FIG. 3, the motor drive circuit 18 comprised by the inverter is connected to the power supply 21 which uses a household alternating current power supply normally. The motor drive circuit 18 is connected to a motor 15 that rotationally drives a rotating body 13 having grindstones 14, 14,... For grinding the surface of the workpiece. Further, a current detector (current value detection means) 19 for detecting a supply current to the motor 15 is connected between the motor 15 and the motor drive circuit 18.

  The current value detected by the current detector 19 is transmitted to the control device 17 connected so as to be capable of data communication. The control device 17 determines the frequency of the motor drive circuit 18 based on the received current value. And control the voltage. The current value detected by the current detector 19 is a supply current to the motor 15, that is, a load current. Therefore, the detected current value varies greatly depending on the load of the grinding apparatus.

  The current detector 19 may be a normal ammeter or a meter relay for detecting a stepped current value. In the case of a meter relay, if the current value is greater than or equal to the set current value, a signal indicating that may be output to the control device 17.

  FIG. 4 is a graph schematically showing time-series fluctuations in the current value detected by the current detector 19 of the grinding apparatus according to the embodiment of the present invention. In FIG. 4, the vertical axis represents the load current value A detected by the current detector 19, and the horizontal axis represents time t.

  Initially, in a state before starting the motor 15, the load current value is A1. The workpiece is placed on the support base 12, the motor 15 is started, and the position of the rotating body 13 in the height direction is determined. Grinding is started in a state where the spindle speed of the motor 15 is reduced to a lower speed than the spindle speed used in normal finish grinding, for example, about half the number of revolutions. When grinding with a low spindle rotation speed, the cutting edges of the grindstones 14, 14,... Can be applied to the surface of the workpiece with a low grinding force, and the black applied to the surface of the workpiece. The skin can be ground effectively. The spindle speed is preferably about 0.4 to 0.6 when the spindle speed used for normal finish grinding is 1. This is because the grinding force of the cutting edges of the grindstones 14, 14,.

  When grinding of the black skin is started, the load current value detected by the current detector 19 is increased by the rotation of the grindstones 14, 14,. When the cutting edge in contact with the grinding surface is lost at the beginning of the grindstones 14, 14,..., The load current value decreases to near A1, and the next cutting edge is the first cutting edge. Grinding with the next cutting edge is resumed when moving to the position where grinding was performed at the time of loss, and the load current value rises again.

  Then, when the second cutting edge is lost, the load current value decreases again to near A1, and the next cutting edge moves to the position where it was ground when the second cutting edge was lost. Then, the grinding with the next cutting edge is resumed, and the load current value rises again. Hereinafter, the above-described variation of the load current value is repeated until the black skin existing on the surface of the workpiece is ground.

  And when the black skin is ground by a predetermined amount, the peak of the load current value greatly decreases to near A2. In the example of FIG. 4, the peak of the load current value is reduced to near A2 at time t1. When the black skin is ground by a predetermined amount, the load current value does not increase any more. Therefore, for example, when the load current value does not exceed A2 for a certain time, it can be determined that the grinding of the black skin is completed. In the example of FIG. 4, since the peak of the load current value decreases to near A2 at time t1, and the load current value does not exceed A2 thereafter, the spindle speed of the motor 15 is set at a predetermined time after time t1. Increase to the spindle speed used for normal finish grinding. When grinding with a high spindle speed, the cutting edges of the grindstones 14, 14,... Can be applied to the surface of the workpiece with a high grinding force.

  After that, finish grinding is executed by the rotation of the grindstones 14, 14,..., And the load current value detected by the current detector 19 increases. When the cutting edge in contact with the grinding surface is lost at the beginning of the grindstones 14, 14,..., The load current value decreases to near A1, and the next cutting edge is the first cutting edge. Grinding with the next cutting edge is resumed when moving to the position where grinding was performed at the time of loss, and the load current value rises again.

  Then, when the second cutting edge is lost, the load current value decreases again to near A1, and the next cutting edge moves to the position where it was ground when the second cutting edge was lost. Then, the grinding with the next cutting edge is resumed, and the load current value rises again. Hereinafter, the variation of the load current value described above is repeated until finish grinding is completed.

  In this way, when grinding is performed with a low spindle speed by changing only the spindle speed of the motor 15 without stopping the rotation of the rotating body 13 during the grinding process, the grindstones 14, 14,...・ When the cutting edge can be applied to the surface of the work piece with a low grinding force and grinding is performed with a high spindle speed, the cutting edges of the grindstones 14, 14,. It can be made to act on the surface of this with high grinding force. Therefore, it is possible to execute both black skin grinding and finish grinding without exchanging the grindstones 14, 14,.

  When the finish grinding is completed, the peak load current value greatly decreases to near A3. In the example of FIG. 4, the peak of the load current value is reduced to near A3 at time t2. When finish grinding is completed, the load current value does not increase any more. Therefore, for example, when the peak of the load current value does not exceed A3 for a certain time, it can be determined that the finish grinding has been completed. In the example of FIG. 4, the peak of the load current value decreases to near A3 at time t2, and the load current value does not exceed A3 thereafter.

  The spindle speed can be changed manually while visually confirming the degree of grinding of the black skin, or visually confirming fluctuations in the load current value detected by the current detector 19, or with the current detector 19. You may perform automatically by the control apparatus 17 based on the detected electric current value. FIG. 5 is a flowchart showing the procedure of the spindle speed changing process of the control device 17 of the grinding device according to the embodiment of the present invention. In FIG. 5, the control device 17 sends a start instruction for the motor 15 to the motor drive circuit 18 (step S501), and starts the constant detection of the current value by the current detector 19 (step S502). The control device 17 receives the output signal of the current detector 19 and grasps the current value.

  The control device 17 sets the spindle speed to a low state, that is, “LOW” (step S503), and sends a grinding start instruction (step S504). The grinding start instruction may be sent to a motor driving circuit in the height direction (not shown) that controls the sliding of the rotating body 13 in the height direction, or the rotating body 13 is lowered by a manual lever (not shown). May be output as a message to a display device or the like.

  The control device 17 determines whether or not the current value detected by the current detector 19 is smaller than the load current value A2 in FIG. 4 (step S505). When the control device 17 determines that the load current value is greater than or equal to the load current value A2 (step S505: NO), the control device 17 waits until it becomes smaller than the load current value A2.

  When it is determined that the control device 17 is smaller than the load current value A2 (step S505: YES), the control device 17 determines whether or not the state smaller than the load current value A2 continues for a predetermined time (step S506). . When the control device 17 determines that the state smaller than the load current value A2 has not continued for a predetermined time (step S506: NO), the control device 17 returns the processing to step S505 and repeats the above-described processing.

  When the control device 17 determines that the state smaller than the load current value A2 continues for a predetermined time (step S506: YES), the control device 17 sets the spindle rotational speed to a high state, that is, “HIGH” ( In step S507), it is determined whether or not the current value detected by the current detector 19 is smaller than the load current value A3 in FIG. 4 (step S508). When the control device 17 determines that the load current value is greater than or equal to the load current value A3 (step S508: NO), the control device 17 waits until it becomes smaller than the load current value A3.

  When it is determined that the control device 17 is smaller than the load current value A3 (step S508: YES), the control device 17 determines whether or not the state smaller than the load current value A3 continues for a predetermined time (step S509). . When the control device 17 determines that the state smaller than the load current value A3 has not continued for a predetermined time (step S509: NO), the control device 17 returns the processing to step S508 and repeats the above-described processing.

  When the control device 17 determines that the state smaller than the load current value A3 continues for a predetermined time (step S509: YES), the control device 17 sends a grinding end instruction (step S510). The grinding end instruction may be sent to a motor driving circuit in the height direction (not shown) that controls the sliding of the rotating body 13 in the height direction, or the rotating body 13 is raised by a manual lever (not shown). The instruction to be displayed may be output as a message to a display device or the like.

  The control device 17 sends an instruction to stop the motor 15 to the motor drive circuit 18 (step S511), and ends the process.

  As described above, according to the present embodiment, by changing only the rotation speed of the spindle of the motor 15 without stopping the rotation of the rotating body 13 during the grinding process of the surface of the workpiece with black skin, When grinding with a low spindle speed, the cutting edges of the grindstones 14, 14,... Can be applied to the surface of the workpiece with a low grinding force, and grinding is performed with a high spindle speed. In this case, the cutting edges of the grindstones 14, 14,... Can be applied to the surface of the workpiece with a high grinding force. Therefore, it is possible to execute both black skin grinding and finish grinding without exchanging the grindstones 14, 14,.

  The degree of coupling of the grindstones 14, 14,... Is not limited to being uniform for all the grindstones 14, 14,..., And the grindstones 14, 14,. May be arranged. FIG. 6 is a bottom view of another rotating body 13 of the grinding apparatus according to the embodiment of the present invention.

  Different from FIG. 2, the grindstones 14, 14,... Arranged at the peripheral portion are alternately arranged with grindstones 14 </ b> L and 14 </ b> K having different degrees of coupling. In the example of FIG. 6, a combination of two grindstones 14L with a hard bond and one grindstone 14K with a soft bond is alternately arranged at the periphery. By doing in this way, the sharpness of a grindstone can be raised by suppressing grinding resistance and grinding heat, and it becomes possible to aim at improvement of grinding efficiency and grinding accuracy. In addition, in the example of FIG. 6, although the coupling degree of the grindstones 14, 14,... Having the same size and shape is periodically changed, the grindstones 14, 14,. However, the present invention is not limited to this and may be arranged in various combinations. That is, the size and shape of the grindstone 14 do not have to be the same, and it is only necessary to change the degree of coupling.

  Further, instead of arranging the plurality of grindstones 14, 14,... At the peripheral portion of the rotating body 13, one annular ring grindstone may be arranged. FIG. 7 is a bottom view of another rotating body 13 of the grinding apparatus according to the embodiment of the present invention.

  Unlike FIG.2 and FIG.6, the grindstone 14 arrange | positioned in the peripheral part is cyclic | annular and united. Therefore, the grindstone can be replaced only once, and complicated work can be avoided.

  It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and substitutions are possible within the scope of the gist of the present invention. For example, in the present embodiment, the grindstones 14, 14,... Are rotated on a surface substantially parallel to the surface of the workpiece, but the main axis of the rotating body 13 is set to the substantially horizontal direction, and the rotating body 13 is rotated. May be rotated on a substantially vertical surface by arranging a plurality of grindstones 14, 14,...

  In addition, the workpiece is not limited to a steel plate with a black skin such as SS400, for example, and may be a metal plate made of a non-ferrous metal material.

  Furthermore, not the method of changing the rotation speed of the rotating body 13, but the method of changing the cutting feed speed, which is the moving speed of the rotating body 13 in the height direction, may be used. When the cutting feed speed is increased, the cutting edge is lost early, and grinding with a new cutting edge can be started. Therefore, the processing efficiency of the grinding process is improved.

12 Support stand (support plate)
DESCRIPTION OF SYMBOLS 13 Rotating body 14 Grinding wheel 15, 22 Motor 17 Control device 19 Current detector (current value detection means)

Claims (11)

A support plate for placing the workpiece;
A rotating body on which a grindstone capable of rotating on a surface substantially parallel to the support plate is disposed;
A grinding apparatus comprising: a motor that rotationally drives the rotating body;
A grinding apparatus, wherein the rotational speed of the rotating body is changed during grinding of the surface of the workpiece by the grindstone. A current value detecting means for detecting a current value of the motor;
2. The grinding apparatus according to claim 1, wherein the rotational speed of the rotating body is changed when a state where the current value detected by the current value detecting means is smaller than a predetermined value continues for a predetermined time. A control device for controlling the spindle speed of the motor;
3. The control device according to claim 2, wherein the controller controls to increase the rotational speed of the spindle of the motor when it is determined that a state in which the current value detected by the current value detection unit is smaller than a predetermined value continues for a predetermined time. Grinding equipment. Having another motor that rotationally drives the support plate in a plane substantially parallel to the rotating body;
4. The rotation speed of the rotating body and the rotation speed of the support plate are changed during grinding of the surface of the workpiece by the grindstone. 5. The grinding apparatus described in 1.   The grinding apparatus according to claim 1, wherein an annular grindstone is disposed on the rotating body.   The grinding device according to any one of claims 1 to 4, wherein the rotating body includes a plurality of grindstones arranged at a peripheral portion.   The grinding apparatus according to claim 6, wherein the plurality of grindstones include grindstones having different coupling degrees. It can be executed by a grinding apparatus having a rotating body on which a grindstone capable of rotating on a surface substantially parallel to a support plate on which a workpiece is placed is arranged, and the rotating body is driven to rotate by a motor. In possible grinding methods,
A grinding method, wherein the rotational speed of the rotating body is changed during grinding of the surface of the workpiece by the grindstone. Detecting the current value of the motor;
9. The grinding method according to claim 8, wherein the number of rotations of the rotating body is changed when a state in which the detected current value is smaller than a predetermined value continues for a predetermined time.   The control device for controlling the rotational speed of the spindle of the motor increases the rotational speed of the spindle of the motor when it is determined that a state in which the detected current value is smaller than a predetermined value continues for a predetermined time. Grinding method. The support plate is rotationally driven on a surface substantially parallel to the rotating body by another motor,
The grinding according to any one of claims 8 to 10, wherein the rotational speed of the rotating body is changed during the grinding of the surface of the workpiece by the grindstone, and the rotational speed of the support plate is changed. Method.

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