JP2005342851A - Double-side machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-side machining device for extra-precisely grinding both sides of a workpiece such as glass of optical parts and a semiconductor silicon wafer capable of improving machining accuracy of the workpiece by considering uneven wear of a pair of machining materials and a measurement error caused by warpage and wave of the workpiece generated between the position of the workpiece determined by a measurement (= estimated positions of the machining materials) and actual positions of the machining materials when adjusting the positions of the machining materials. <P>SOLUTION: This device is provided with two position sensors 45a and 45b for acquiring position data of a surface to be machined of the workpiece for every time machining of the workpiece is finished, a grinding tool wear amount calculation means 65 for calculating wear amount of a cup type grinding tool based on a grinding tool target position R of the surface to be machined of the workpiece of the lst sheet at the time of finishing the machining, the position of the surface to be machined of the workpiece of the mth sheet and displacement amount at a feeding position of a grinding spindle, and a grinding tool position correction amount calculation means for calculating correction amount to correct the machining finishing position of the cup type grinding tool to the grinding tool target position R based on the wear amount. The correction amount is fed back to the grinding tool position control means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a double-sided processing apparatus, and more particularly, to a double-sided processing apparatus that ultra-precisely grinds both sides of a workpiece such as glass of an optical component or a semiconductor silicon wafer.

  A double-sided processing device for processing both sides of a thin circular workpiece (workpiece) such as a semiconductor wafer or a glass substrate for a hard disk with a pair of processing members includes a workpiece holding device for rotatably supporting the workpiece. It has been.

  The double-sided processing device includes a double-sided grinding device and a double-sided polishing device that processes a workpiece with higher accuracy than a double-headed grinding device. In the double-head grinding apparatus, both surfaces of the work that is rotationally supported by the work holding device are simultaneously ground by a pair of cup-type grindstones that rotate to face each other. In the case of a double-side polishing apparatus, the polishing liquid is supplied between the polishing cloths by sandwiching the work supported by the work holding device between a pair of surface plates to which the polishing cloth is attached, and the pair of surface plates are rotated. Thus, both sides of the workpiece are polished simultaneously.

  In such a double-sided processing apparatus, in order to process both sides of the workpiece with high accuracy, before performing the double-sided processing of the work, the work surface of the work supported by the work holding device and the processing surface of the pair of cup-type grindstones Optimum positional relationship by adjusting the positional relationship (in the case of double-head grinding device) or the positional relationship between the workpiece surface supported by the workpiece holding device and the machining surface of the pair of surface plates (in the case of a double-side polishing device) Is done.

  However, in the case of a double-head grinding machine, as the cumulative number of workpieces to be processed increases, the wear amount of a pair of cup-type grinding wheels varies due to minute differences in grinding conditions, and the workpiece coverage optimized prior to machining is increased. There has been a problem that the processing accuracy of both surfaces of the workpiece is lowered because the positional relationship between the processing surface and the processing surface of the pair of cup-type grindstones deviates from the optimized state. In addition, in the case of a double-side polishing machine, as the cumulative number of workpieces processed increases, the wear amount of the pair of polishing cloths varies due to minute differences in polishing conditions, and the workpiece to be optimized before processing is processed. The positional relationship between the surface and the processed surface of the pair of polishing cloths deviates from the optimized state, and there is a problem that the processing accuracy of both surfaces of the workpiece is lowered.

  As a conventional double-side grinding apparatus for solving such problems, a pair of fluid supply members are provided with bending detection means for detecting the amount of bending of a workpiece when a pair of grindstones contact the workpiece. The distance between the fluid supply member and the work surface of the workpiece is measured to detect the bending amount of the workpiece, and when the bending amount of the workpiece exceeds the predetermined amount, the grinding operation of the pair of grinding stones after the grinding process is completed There is one that changes the standby position of a pair of grindstones so that the surface position is optimal (see, for example, Patent Document 1).

In the conventional double-side processing apparatus, a means for detecting the position of the holding means for holding the workpiece, a means for detecting the position of the grinding operation surface of the pair of grindstones, a computer for processing the detection results, and a computer A holding means and / or a means for moving the position of the grinding wheel on the basis of the processed information, and the center of the workpiece thickness and / or the center of the holding means and the center of the grinding operation surface of the pair of grinding stones. There is one in which warpage of the workpiece is suppressed by performing double-sided machining of the workpiece while always matching (see, for example, Patent Document 2).
JP 2002-307303 A International Publication No. WO00 / 67950 Pamphlet

  By the way, the workpiece has warpage and undulation, and when machining the workpiece, a vibration occurs in the virtual center plane of the rotated workpiece, thereby lowering the machining accuracy of the workpiece.

  However, since the double-side grinding apparatus provided with the bending detection means does not consider the warping or waviness of the workpiece, the bending of the workpiece obtained by measuring the distance between the pair of fluid supply members and the work surface of the workpiece. The reliability of the amount is lowered, and there is a problem that it is difficult to adjust the position of the grindstone so that the position of the grinding operation surface at the time of completion of the grindstone cutting is optimized. Further, in a double-side grinding apparatus equipped with a bending detection means, the distance between the bending detection means and the work surface of the workpiece is measured by air, but when the distance between the bending detection means and the workpiece is close However, there is a problem that the work cannot be processed with high accuracy because the work is pushed by the air pressure (the work receives external force). Furthermore, since the influence of the case where the wear amount of the pair of grindstones is different (uneven wear of the grindstone) is not taken into account, there is a problem that it is difficult to machine the workpiece with high accuracy.

  In the conventional double-side processing apparatus, no consideration is given to how to measure the center of the thickness of the workpiece and / or the center of the holding means for holding the workpiece and the center of the grindstone surface interval between the pair of grindstones. Therefore, it is difficult to control so that the center of the thickness of the workpiece and / or the center of the holding means that holds the workpiece and the center of the grindstone surface interval of the pair of grindstones always coincide.

  In addition, since warpage and waviness of the workpiece and an error (hereinafter referred to as a measurement error) generated between the position of the workpiece (= the position of the grindstone) obtained from the measuring device and the actual position of the grindstone are not considered. It is difficult to match the center of the thickness of the workpiece and / or the center of the holding means for holding the workpiece with the center of the grindstone surface interval between the pair of grindstones, and there is a problem that the workpiece cannot be processed with high accuracy. It was.

  Further, in order to perform correction and control in real time so that the center of the thickness of the workpiece and / or the center of the holding means for holding the workpiece and the center of the grindstone surface interval of the pair of grindstones always coincide with each other, a separate control device is used. There was a problem that had to be established. Moreover, since the influence when the amount of wear of a pair of grindstones is different (hereinafter referred to as grindstone uneven wear) is not considered, there is a problem that it is difficult to machine a workpiece with high accuracy.

  Therefore, the present invention has been made in view of the above points, and when adjusting the position of a pair of processing members, the processing member uneven wear and the position of the workpiece obtained by measurement (= estimated processing member) A double-sided processing device that can improve the processing accuracy of the workpiece in consideration of measurement errors caused by warpage and waviness of the workpiece that occur between the position of the workpiece and the actual position of the workpiece The purpose is to do.

  In order to solve the above-mentioned problems, the present invention is characterized by the following measures.

  According to the first aspect of the present invention, a pair of processing members for processing both surfaces of a rotationally supported workpiece, a main shaft provided integrally with the processing member, and a grindstone position control means for controlling the position of the main shaft. A spindle position sensor that detects the feed position of the spindle, two position sensors that acquire position data of a workpiece surface of the workpiece each time machining of the workpiece, Based on the target position of the workpiece surface of the workpiece, the position of the workpiece surface of the workpiece, and the displacement of the feed position of the spindle, the amount of wear generated in each workpiece is calculated, and Wear correction amount calculating means for calculating a correction amount for correcting the processing end position of each processing member to the target position based on the wear amount, and feedback means for feeding back the correction amount to the grindstone position control means. Establishment The double-sided processing apparatus characterized by, can be solved.

  According to the above-mentioned invention, it is generated in each workpiece based on the target position of the workpiece surface of the workpiece at the end of machining, the position of the workpiece surface of the workpiece, and the displacement of the feed position of the spindle. While calculating the amount of wear, based on the amount of wear, wear correction amount calculating means for calculating a correction amount for correcting the processing end position of each processing member to the target position, and feedback for feeding back the correction amount to the grindstone position control means A correction amount is fed back to the grinding wheel position control means so that the processing end position of each processing member becomes substantially the same as the target position of the processing surface of the workpiece, and the position of each processing member is adjusted. Thus, the workpiece can be processed with high accuracy.

  2. The double-sided machining apparatus according to claim 1, wherein the wear correction amount calculating means includes a filter for removing a component caused by a rotation cycle of the work included in the position data. Can be solved.

  According to the above invention, since the component due to the rotation period of the workpiece included in the position data in the wear correction amount calculation means is removed by the filter, the accuracy of the position data is improved, and therefore the machining end position of each machining member It is possible to improve the accuracy of the correction amount for correcting the position to the target position.

  According to a third aspect of the present invention, the wear correction amount calculating means corrects the steady component and the fluctuation component, which are wear components generated by machining, and reflects them in the processing of the wear correction amount calculating means. To the correction amount due to a measurement error generated between the position of the workpiece surface of the workpiece detected by two position sensors and the position of the workpiece surfaces of the pair of workpiece members at the end of machining of the workpiece The problem can be solved by the double-sided processing apparatus according to claim 1 or 2, wherein the influence is reduced.

  According to the above invention, the wear correction amount calculation means corrects the steady component and the fluctuation component, which are wear components generated by machining, and reflects them in the processing of the wear correction amount calculation means, and is also detected by the two position sensors. By reducing the influence on the correction amount due to the measurement error that occurs between the position of the processed surface of the processed workpiece and the position of the processed surface of the pair of processed members at the end of processing of the workpiece Therefore, it is possible to improve the accuracy of the correction amount obtained by the above.

  According to a fourth aspect of the present invention, the wear correction amount calculating means includes a grindstone position estimation filter that removes the component of the measurement error. It can be solved by the device.

  According to the above invention, the accuracy of the correction amount can be improved by providing the wear correction amount calculating means with the grindstone position estimation filter for removing the component of the measurement error.

According to a fifth aspect of the present invention, the wear correction amount calculation means calculates a correction amount of the position of the machining surface of the pair of machining members at the end of machining so as to remove the steady component and the fluctuation component by a second order integral component. 5. The double-sided processing apparatus according to claim 1, wherein the steady-state component and the fluctuation component can be effectively removed by the second-order integral component. .

  According to a sixth aspect of the present invention, the wear correction amount calculating means is configured to remove the steady component and the fluctuation component by the second-order integral component and the first-order integral component, so that the machining surfaces of the pair of machining members at the end of machining are removed. The position correction amount is calculated, which can be solved by the double-sided processing apparatus according to any one of claims 1 to 5.

  According to the above invention, the steady component and the fluctuation component can be removed by the second-order integral component and the first-order integral component.

  According to a seventh aspect of the present invention, the wear correction amount calculating means is configured to remove the steady component and the fluctuation component by the second order integration component, the first order integration component, and the proportional component, and the pair of processing at the end of processing. The problem can be solved by the double-sided processing apparatus according to any one of claims 1 to 6, wherein the correction amount of the position of the processed surface of the member is calculated.

  According to the above invention, the steady component and the fluctuation component can be removed by the second-order integral component, the first-order integral component, and the proportional component.

  According to an eighth aspect of the present invention, the two position sensors are cylinder pressure contact type position sensors, and can be solved by the double-sided processing apparatus according to any one of the first to seventh aspects. .

  According to the invention, by using a cylinder pressure contact type position sensor for the two position sensors, when the workpiece is pressed by the two position sensors, the force received from both sides of the workpiece surface of the workpiece Is offset to prevent an external force from being applied to the workpiece, and the machining accuracy of the workpiece can be improved.

  In the invention according to claim 9, the two position sensors are non-contact sensors, and can be solved by the double-sided processing apparatus according to any one of claims 1 to 8.

  According to the above invention, by using a non-contact sensor for the two position sensors, when the two position sensors measure the workpiece surface of the workpiece, the two position sensors may contact the workpiece. The workpiece can be processed with high accuracy.

  In the present invention, when adjusting the positions of a pair of processing members, the uneven wear of the processing members, the position of the workpiece obtained by measurement (= the estimated position of the processing member), and the actual position of the processing member It is an object of the present invention to provide a double-sided processing apparatus capable of improving the processing accuracy of a workpiece in consideration of measurement errors caused by warping and waviness of the workpiece generated in the meantime.

  Next, embodiments of the present invention will be described with reference to the drawings.

  First, a double-head grinding apparatus 10 to which the wear correction amount calculating means 60 and the grindstone position control means 68 of the present invention are applied will be described with reference to FIG. FIG. 1 is a view showing a double-head grinding apparatus which is an embodiment of the present invention. In FIG. 1, Y and Y directions indicate directions in which the cup-type grindstones 20a and 20b move relative to the workpiece 50 (thrust direction), and X and X directions indicate movement directions of the cup-type grindstones 20a and 20b. The direction (radial direction) orthogonal to is shown.

  The double-head grinding apparatus 10 is roughly configured to include a double-head grinding apparatus main body 15, a wear correction amount calculation means 60, and a grindstone position control means 68.

  The double-head grinding device main body 15 is configured to include grinding devices 16a and 16b, a base 17, spindle position sensors 120a and 120b, and a work holder 25. Two grinding devices 16a and 16b are arranged so that the same configuration faces each other across the workpiece 50 (work holder 25). In FIG. 1, the symbol a is added to the grinding device 16a located on the right side in the figure, the symbol b is added to the grinding device 16b located on the left side in the figure, and the grinding device 16a is mainly described. To do.

  The grinding device 16a generally includes a cup-type grindstone 20a, a grinding spindle 22a, a saddle 23a, a saddle driving device 18a, and a rotation driving device (not shown). The cup-type grindstone 20a is integrally provided at one end of the grinding spindle 16a. In the cup-type grindstone 20a, a flat grinding operation surface 21a is formed on the end surface on the open side of the cup (the surface on which the abrasive grains are fixed). The grinding operation surfaces 21a and 21b are set so as to pass through the rotation center position C of the workpiece 50 (see FIG. 2), and both surfaces of the workpiece 50 are ground simultaneously by the grinding operation surfaces 21a and 21b.

  The grinding spindle 16a is provided with a rotation drive device (not shown). The rotation drive device is for rotating the grinding spindle 16a in the X and X directions. When the grinding spindle 16a rotates, the cup-type grindstone 20a also rotates integrally.

  The other end of the grinding spindle 16a is fixed to the saddle 23a. The saddle 23a is provided on the base 17, and is configured to be movable on the base 17 in the Y and Y directions. A saddle driving device 18a is provided at the end of the saddle 23a on the side where the grinding spindle 16a is not provided. The saddle driving device 18a is for moving the saddle 23a in the Y and Y directions. When the saddle 23a moves, the grinding spindle 16a also moves integrally.

  The spindle position sensor 120a detects the position of the saddle 23a. The distance from the measurement position of the spindle position sensor 120a to the grinding operation surface 21a of the cup-type grindstone 20a is added to the measurement value of the spindle position sensor 120a, and the grinding wheel position control means 68 is based on this added value (hereinafter referred to as offset amount). Thus, the position of the grinding operation surface 21a of the cup-type grindstone 20a and the feed amount of the cup-type grindstone 20a are controlled. The spindle position sensor 120b has the same configuration as the spindle position sensor 120a. The position data Sa and Sb detected by the spindle position sensors 120a and 120b are transmitted to the grindstone wear amount calculating means 65 described later.

  A workpiece 50 rotatably supported by a workpiece holder 25 to be described later is ground by being brought into contact with the grinding operation surfaces 21a and 21b of the pair of cup-type grindstones 20a and 20b that rotate.

  Next, the work holder 25 will be described with reference to FIG. FIG. 2 is a view of the work holder shown in FIG.

  In general, the work holder 25 includes a work holder frame 26, a roller driving unit 27, two driving roller units 33, a driving belt 38, three supporting roller units 41, and position sensors 45a and 45b. It is set as the structure with these. In addition, the workpiece holder 25 is configured such that the workpiece 50 can be attached and detached by an opening / closing mechanism (not shown).

  The roller drive unit 27 includes a drive motor 28, a rotation shaft 29, and a pulley 31, and is provided at a position separated from the work 50 of the work holder frame 26. The drive motor 28 is connected to the pulley 31 via the rotating shaft 29, and the pulley 31 also rotates when the drive motor 28 rotates. The roller driving unit 27 is for rotating the grooved roller 35 provided in the driving roller unit 33.

  Two driving roller portions 33 are provided on the work holder frame 26, and have a grooved roller 35, a rotation shaft 34, and a pulley 36. The driving roller portion 33 is provided at a position corresponding to the vicinity of the outer peripheral portion of the workpiece 50. The grooved roller 35 is connected to a pulley 36 via a rotating shaft 34. The grooved roller 35 has a groove (not shown) for making contact with the outer peripheral end of the workpiece 50. The two pulleys 36 are connected to the pulley 31 via the drive belt 38, and the rotation when the pulley 31 is rotated by the drive motor 28 is transmitted to the two pulleys 36 via the drive belt 38. Two grooved rollers 35 rotate to rotate the workpiece 50.

  Three supporting roller portions 41 are provided and have a grooved roller 43 and a rotating shaft 42. The supporting roller portion 41 is provided at a position corresponding to the vicinity of the outer peripheral portion of the workpiece 50. The support roller portion 41 is for rotatably supporting the workpiece 50. The grooved roller 43 has a groove (not shown) for contacting the outer peripheral end of the workpiece 50. The rotating shaft 42 is formed integrally with the grooved roller 43.

  The position sensor 45a is a cylinder pressurization type contact sensor, and roughly includes a position sensor main body 46a, a contact 47a, and a cylinder pressurization unit (not shown). The position sensor main body 46a extends on the work surface 50a of the workpiece 50, and a contactor 47a is provided at the end thereof. The contact 47a is disposed so as to come into contact with the work surface 50a of the workpiece 50 by the cylinder pressurizing unit. The position sensor 45a is a sensor for detecting the position of the work surface 50a of the workpiece 50 before and after the start of the grinding process and during the grinding process, and the detected position data Ea is always a filter 61a described later and the thickness of the workpiece. It is transmitted to the calculation means 62.

  The position sensor 45b is a cylinder pressurization type contact sensor, and roughly includes a position sensor main body 46b, a contact 47b, and a cylinder pressurization unit (not shown). The position sensor main body 46b extends on the work surface 50b of the workpiece 50, and a contact 47b is provided at the end thereof. The contact 47b is disposed so as to come into contact with the work surface 50b of the workpiece 50 by the cylinder pressing portion. The position sensor 45b is a sensor for detecting the position of the work surface 50b of the workpiece 50 before and after the start of the grinding process and during the grinding process. The detected position data Eb is always the filter 61b described later and the thickness of the workpiece. It is transmitted to the calculation means 62.

  By providing such cylinder pressure type position sensors 45a and 45b on the processed surfaces 50a and 50b of the workpiece 50, the force received by the processed surfaces 50a and 50b of the workpiece 50 when the contacts 47a and 47b are pressed. Can be offset to prevent an excessive external force from being applied to the workpiece, and the machining accuracy of the workpiece 50 can be improved. In the present embodiment, the case where the cylinder pressure type position sensors 45a and 45b are applied is described as an example. However, the position sensors 45a and 45b include non-contact type sensors such as an optical position sensor and an eddy current type displacement sensor. A sensor may be used. When a non-contact sensor such as an optical position sensor or an eddy current displacement sensor is used, the positions of the work surfaces 50a and 50b of the workpiece 50 can be detected without applying an external force to the workpiece 50. Therefore, the workpiece 50 can be ground with high accuracy.

  Here, with reference to FIG. 3, the data component included in the position data Ea will be described by taking as an example a case where one workpiece 50 is ground.

  FIG. 3 is a diagram for explaining components included in the position data acquired by the position sensor. In FIG. 3, the vertical axis represents the thickness of the cup-type grindstone 20a, and the horizontal axis represents the grinding time of the workpiece 50 by the cup-type grindstone 20a. Further, t1 is a grinding process start time (hereinafter referred to as a process start time t1), t2 is a grinding process end time (hereinafter referred to as a process end time t2), and G is a period from immediately after the start of the grinding process to the end of the grinding process. Position data Ea (hereinafter referred to as a position data curve G) detected by the position sensor 45a, H is an ideal machining surface position curve (hereinafter referred to as an ideal machining surface position curve H) of the cup-type grindstone 20a, and I is The position of the grinding operation surface 21a of the cup-type grinding wheel 20a before grinding, g is a measured value of the grinding operation surface 21a of the cup-type grinding stone 20a at the end of grinding processing, and M1 is grinding of the cup-type grinding stone 20a when machining one workpiece. A displacement amount measurement value (hereinafter referred to as a displacement amount measurement value M1) of the operation surface 21a, M2 is a displacement amount of the grinding operation surface 21a of the cup-type grindstone 20a when machining one workpiece obtained from the ideal machining surface position curve H. Value (hereinafter referred to as displacement ideal value M2), M3 is the difference between the displacement amount measurement value M1 and displacement ideal value M2 are respectively (hereinafter, the error M3 to) a. The ideal machining surface position curve H is a curve having a data component of only the wear amount of the grinding operation surface 21a of the cup-type grindstone 20a.

  As described above, the workpiece 50 has warpage and undulation. In the double-head grinding apparatus 10, the workpiece 50 having such warpage and undulation is rotated and supported by the workpiece holder 25, and the workpiece 50 is ground by the grinding operation surfaces 21b and 21b of the pair of cup-type grindstones 20b and 20b. To do. Therefore, the position data curve G of the work surface 50a of the work 50 detected by the position sensor 45a is generated by the rotation of the work 50 having warpage and waviness in addition to the data related to the wear amount of the cup-type grindstone 20a. The noise etc. (henceforth the disturbance component resulting from the workpiece | work 50) resulting from the rotation period of the workpiece | work 50 to be included are contained. Therefore, as shown in FIG. 3, the position data curve G becomes a wavy curve, and between the grinding wheel wear amount M1 by the position data curve G and the grinding wheel wear amount M2 by the ideal machining surface position curve H at the machining end time t2. In addition, a difference M3 in the grinding wheel wear amount occurs.

  The difference M3 in the grinding wheel wear amount is obtained by filtering the position data Ea with a filter 61a, which will be described later, so that noise caused by the rotation period of the workpiece 50 generated by the rotation of the workpiece 50 having warpage and waviness is removed. Thus, the position data curve G can be approximated to the ideal machining surface position curve H. Note that the position data Eb also includes data components of the same type as the data component of the position data Ea. The position data Eb is band-limited by a filter 61b described later.

  Next, the wear correction amount calculation means 60 will be described with reference to FIG. The wear correction amount calculation means 60 is roughly composed of filters 61a and 61b, a workpiece thickness calculation means 62, a storage means 63, a grinding process end detection means 64, a grindstone wear amount calculation means 65, and a second storage means 66. And a grindstone position correction amount calculating means 67 and a grindstone position control means 68.

  The filter 61a is a low-pass filter whose cut-off frequency is equal to or lower than the rotation speed of the workpiece 50, and is connected to the position sensor 45a, the storage unit 63, and the grinding process end detection unit 64. The filter 61a is a disturbance component caused by the workpiece 50 (a component caused by the rotation cycle of the workpiece 50 generated by the rotation of the workpiece 50 having warpage or undulation) from the position data Ea transmitted from the position sensor 45a. This is for removing only a high-frequency component and acquiring only data relating to the position of the cup-type grindstone 20a. Further, when the filter 61a receives the machining end detection signal from the grinding process end detection means 64, the filter 61a obtains position data Eaf (data after the filter process) related to the positions of the workpiece surfaces 50a and 50b of the workpiece 50 for which the grinding process has been completed. Transmit to the storage means 63.

  The filter 61b is a low-pass filter whose cut-off frequency is equal to or lower than the rotation speed of the workpiece 50, and is connected to the position sensor 45b, the storage unit 63, and the grinding process end detection unit 64. The filter 61b is a disturbance component caused by the workpiece 50 (a component caused by the rotation cycle of the workpiece 50 generated by the rotation of the workpiece 50 having warpage or undulation) from the position data Eb transmitted from the position sensor 45b. This is for removing only a high-frequency component and acquiring only data relating to the position of the cup-type grindstone 20b. Further, the filter 61b receives position data Ebf (filtered data) related to the positions of the processed surfaces 50a and 50b of the workpiece 50 after the grinding process when receiving the machining end detection signal from the grinding process end detection means 64. Transmit to the storage means 63.

  The workpiece thickness calculation means 62 is connected to the position sensors 45a and 45b and the grinding process end detection means 64. The workpiece thickness calculating means 62 is for calculating the thickness W of the workpiece 50 by calculation based on the position data Ea and Eb transmitted from the position sensors 45a and 45b. The position data Ea and Eb are transmitted to the workpiece thickness calculation means 62 before the grinding process is started and until the grinding process is completed. The workpiece thickness calculation means 62 transmits the workpiece thickness W from before the start of the grinding process to the end of the grinding process to the grinding process end detection means 64 in real time.

  The storage unit 63 is connected to the filters 61 a and 61 b, the grinding process end detection unit 64, and the grindstone wear amount calculation unit 65. The storage means 63 is for storing the position data Eaf, Ebf of the workpiece surfaces 50a, 50b of the workpiece 50 transmitted from the filters 61a, 61b at the end of the grinding process. In addition, for example, when the n number of workpieces 50 are ground, the storage unit 63 receives up to m (1 <m <n) th workpieces when receiving a machining end detection signal from the grinding end detection unit 64. 50 (hereinafter, the m-th workpiece is indicated as workpiece 50 (m)), the position data Eaf-1 at the end of the grinding of the first workpiece 50 (1), Ebf-1 and position data Eaf-m and Ebf-m at the end of grinding of the m-th workpiece 50 (m) are transmitted to the grindstone wear amount calculating means 65.

  The grinding end detection means 64 is connected to the workpiece thickness calculation means 62, the storage means 63, and the second storage means 66. The grinding work end detection means 64 is inputted in advance with a desired thickness W1 of the workpiece 50 at the end of the grinding work, and the thickness W of the work 50 transmitted from the workpiece thickness calculation means 62 becomes equal to the thickness W1. At this time, a machining end detection signal of the workpiece 50 is transmitted to the storage means 63 and the second storage means 66.

  The grindstone wear amount calculating means 65 is connected to the storage means 63, the spindle position sensors 120 a and 120 b, and the grindstone position correction amount calculating means 67. The grindstone wear amount calculation means 65 includes position data Sa and Sb of the saddles 23a and 22b (position data of the grinding spindles 22a and 22b) from the spindle position sensors 120a and 120b, and the first workpiece 50 (1) from the storage means 63. When the position data Eaf-1 and Ebf-1 at the end of the grinding process and the position data Eaf-m and Ebf-m at the end of the grinding process of the m-th workpiece 50 (m) are received, each cup type This is for calculating the wear amount of the grindstones 20a, 20b.

  Here, with reference to FIG. 4, the calculation method of the abrasion amount of each cup type grindstone 20a, 20b is demonstrated. FIG. 4 is a diagram for explaining a method of calculating the wear amount of the cup-type grindstones 20a and 20b. In FIG. 4, the cup-type grindstones 20a and 20b at the end of grinding of the first workpiece 50 (1) are shown above, and the cup-type grindstone at the end of grinding of the m-th workpiece 50 (m). 20a and 20b are shown below, and the same code | symbol is attached | subjected to the same component as FIG.

  In FIG. 4, Ka1 is the thickness of the cup-type grindstone 20a at the end of grinding of the first workpiece 50 (1) (hereinafter referred to as the grindstone thickness Ka1), and Kb1 is the first workpiece 50 (1). The thickness of the cup-type grindstone 20b at the end of the grinding process (hereinafter referred to as the grindstone thickness Kb1), Eaf-1 and Ebf-1 are the positions of the workpiece 50 (1) at the end of the grinding process (hereinafter referred to as the workpiece). Positions Eaf-1, Ebf-1), Sa1 is the feed position of the grinding spindle 22a at the end of grinding of the first workpiece 50 (1) (hereinafter referred to as feed position Sa1), and Sb1 is the first workpiece 50 ( 1) The feed position of the grinding spindle 22b at the end of grinding (hereinafter referred to as feed position Sb1), Kam is the thickness of the cup-type grindstone 20a at the end of grinding of the m-th workpiece 50 (m) (hereinafter referred to as the grindstone). Thickness Kam), Kbm is the mth workpiece 50 ( ) Of the cup-type grindstone 20b at the end of the grinding process (hereinafter referred to as the grindstone thickness Kbm), Eafm and Ebfm are the positions of the work surface of the workpiece 50 (m) at the end of the grinding process (hereinafter referred to as the work position Eafm, Ebfm) and Sam are the feed position of the grinding spindle 22a at the end of grinding of the m-th workpiece 50 (m) (hereinafter referred to as feed position Sam), and Sbm is the end of grinding of the m-th workpiece 50 (m). The feed position of the grinding spindle 22b (hereinafter, feed position Sbm) is shown.

  Since the saddle driving devices 18a and 18b of the double-head grinding device 15 move symmetrically, Qa (= Sa1-Sam) and Qb (= Sb1-Sbm) are equal (Qa = Qb).

  Since the workpieces 50 (1) and 50-m are processed to a thickness W1, assuming that the wear amount Uam of the cup-type grindstone 20a and the wear amount Ubm of the cup-type grindstone 20b, the wear amounts Uam of the cup-type grindstones 20a and 20b. , Ubm is equal to the sum of the excess cut amounts, and Uam + Ubm = 2Qa. Deviation amount between grinding operation surfaces 21a and 21b at the end of grinding of the first workpiece 50 (1) and grinding operation surfaces 21a and 21b at the end of grinding of the mth workpiece 50 (m). Pa and Pb are represented by Pa = Eafm−Eaf1 and Pb = Ebfm−Ebf1, respectively, and the workpieces 50 (1) and 50−m are processed to a thickness W1, and therefore Pa = Pb. Further, the deviation amounts Pa and Pb are generated by the difference between the wear amounts Uam and Ubm (= Ubm−Uam) of the cup-type grindstones 20a and 20b, and the workpieces 50 (1) and 50-m are processed to a thickness W1. Therefore, Ubm−Uam = 2 Pa.

  Thus, by calculating | requiring the sum (= Ubm + Uam) of abrasion amount Uam, Ubm of cup type grindstone 20a, 20b, and the difference (= Ubm-Uam) of abrasion amount Uam, Ubm of cup type grindstone 20a, 20b, The wear amount Uam (= Qa-Pa) of the cup-type grindstone 20a and the wear amount Ubm (= Qa + Pa) of the cup-type grindstone 20b can be obtained, respectively, and when the correction amount of the position of the cup-type grindstone 20a, 20b is obtained. Therefore, the work 50 can be machined with high accuracy by obtaining an accurate correction amount.

  The grindstone position correction amount calculating means 67 is connected to the grindstone wear amount calculating means 65 and the grindstone position control means 68. The grindstone position correction amount calculating means 67 removes disturbance components due to the workpiece 50 from the wear amounts Uam and Ubm of the cup type grindstones 20a and 20b obtained by the grindstone wear amount calculating means 65, and the cup type grindstones 20a and 20b. This is for calculating a correction amount for correcting the machining end position to the target position R (the position of the cup-type grindstones 20a, 20b at the end of machining the first workpiece).

  In the wear amounts Uam and Ubm of the cup-type grindstones 20a and 20b obtained by the grindstone wear amount calculation means 65, there are many stationary components and low-frequency components in addition to the wear amounts of the cup-type grindstones 20a and 20b. Therefore, in order to obtain an accurate correction value based on the wear amounts Uam and Ubm of the cup-type grindstones 20a and 20b, correction for removing a steady component and a low-frequency component that are noise components from the wear amounts Uam and Ubm. Done. Hereinafter, the correction for reducing the steady component and the low frequency component is referred to as a first correction.

  Here, with reference to FIG. 5 thru | or FIG. 6, the reduction | restoration method of the stationary component and low frequency component which are contained in the abrasion amount Uam of the cup type grindstone 20a, 20b performed by the 1st correction means and Ubm is demonstrated. FIG. 5 is a diagram showing the power spectrum of the grinding wheel wear amount, and FIG. 6 is a transfer function (gain) from the grinding wheel wear amount having the frequency characteristics shown in FIG. 5 to the grinding operation surface at the end of machining. FIG. Here, the power spectrum is the intensity distribution of the frequency component of the signal. The transfer function indicates the signal transfer from the input to the output of the system. Therefore, the result of multiplying the power spectrum of the grinding wheel wear amount by the transmission characteristic from the grinding wheel wear amount to the grinding operation surface at the end of processing becomes the frequency characteristic of the fluctuation of the grinding operation surfaces 21a and 21b caused by the grinding wheel wear amount.

  The power spectrum of the grindstone wear amount shown in FIG. 5 shows the frequency characteristics of the wear amounts Uam and Ubm of the cup-type grindstones 20a and 20b for each number of processed sheets, from a fluctuation component of a period of several tens or more to a steady component. Is the main ingredient.

  In FIG. 6, the frequency 1 / T at which the gain becomes 0.5 is designed in the grindstone position correction amount calculation means 67, so that the influence of the steady component and fluctuation component of the grindstone wear amount on the grinding operation surfaces 21 a and 21 b is affected. Can be reduced. When reducing the influence of the steady component and fluctuation component of the grinding wheel wear amount, the correction amount can be obtained from the sum of the proportional component, the first order integral component, and the second order integral component multiplied by an appropriate coefficient. . The proportional component is obtained by multiplying the grinding wheel wear amount Wm in one machining by an appropriate coefficient (the grinding wheel wear amount when the m-th workpiece 50 (m) is machined is Wm). . The first-order integral component is obtained by multiplying the first-order integral value represented by the following equation (1) obtained by adding the grinding wheel wear amount Wm in one machining with the first wear amount by an appropriate coefficient.

２階積分成分とは、毎回算出される１階積分値（下記（１）式で示される）をさらに1回目から足し合わせた下記（２）式で示される２階積分値に適当な係数を乗じたものである。２階積分成分を用いることで、図５に示した曲線周波数特性に含まれる定常成分（周波数が０のところの成分）と、変動成分（数１０枚以上の長周期の変動成分）とを効果的に減衰させることができる。

The second-order integral component is an appropriate coefficient for the second-order integral value represented by the following equation (2), which is obtained by adding the first-order integral value (expressed by the following equation (1)) calculated each time from the first time. It is multiplied. By using the second-order integral component, the steady component (the component where the frequency is 0) and the fluctuation component (the fluctuation component having a long period of several tens or more) included in the curve frequency characteristics shown in FIG. 5 are effective. Can be attenuated.

また、本発明では、研削加工終了時のワーク５０の被加工面５０ａ，５０ｂの位置を研削加工終了時の研削動作面２１ａ，２１ｂとして代用しているため、研削加工終了時のワーク５０の被加工面５０ａ，５０ｂの位置と研削加工終了時の実際の研削動作面２１ａ，２１ｂの位置との間に計測誤差が生じる。したがって、精度の良い補正値を求める際には、この計測誤差を低減する必要がある。この計測誤差の低減は、第２の補正手段により行われる。

In the present invention, since the positions of the work surfaces 50a and 50b of the workpiece 50 at the end of the grinding process are used as the grinding operation surfaces 21a and 21b at the end of the grinding process, Measurement errors occur between the positions of the processed surfaces 50a and 50b and the actual positions of the grinding operation surfaces 21a and 21b at the end of the grinding process. Therefore, when obtaining a highly accurate correction value, it is necessary to reduce this measurement error. This measurement error is reduced by the second correction means.

  Here, the second correction for reducing the measurement error will be described with reference to FIGS. FIG. 7 is a diagram showing a power spectrum of measurement error, and FIG. 8 shows a transfer function (gain) from the measurement error having the frequency characteristics shown in FIG. 7 to the grinding operation surface at the end of machining. FIG. Therefore, the result of multiplying the power spectrum of the measurement error by the transmission characteristic from the measurement error to the grinding operation surface at the end of machining becomes the variation frequency characteristic of the grinding operation surfaces 21a and 21b caused by the measurement error.

  The frequency characteristic (power spectrum) of the measurement error shown in FIG. 7 has a strong intensity of a short period (high frequency) component caused by an error of the warp amount of the workpiece 50, and has a peak wavelength near the left side of the frequency 1/1. doing.

  FIG. 8 is a diagram showing a transfer function from the measurement error shown in FIG. 7 to the grinding operation surfaces 21a and 21b at the end of machining, where the horizontal axis represents frequency and the vertical axis represents gain. In FIG. 8, the frequency 1 / T that attenuates the transfer function having a gain of 0.5 or less is designed in the grindstone position correction amount calculation means 67, so that the influence of the measurement error on the positions of the grinding operation surfaces 21a and 21b is achieved. Can be reduced. When reducing the influence of the measurement error on the grinding operation surfaces 21a and 21b, the correction amount can be obtained from the sum of each of the proportional component, first-order integral component, and second-order integral component multiplied by an appropriate coefficient. .

  The proportional component is obtained by multiplying the grinding wheel wear amount Wm in one machining by an appropriate coefficient (the grinding wheel wear amount when the m-th workpiece 50 (m) is machined is Wm). . The first-order integral component is obtained by multiplying the first-order integral value represented by the above equation (1), which is obtained by adding the grinding wheel wear amount Wm in one machining operation from the first wear amount, by an appropriate coefficient.

  The second-order integral component means that an appropriate coefficient is added to the second-order integral value represented by the above equation (2), which is obtained by adding the first-order integral value (expressed by the above equation (1)) calculated each time from the first time. It is multiplied. By using the second order integral component, the measurement error included in the curve frequency characteristic shown in FIG. 8 can be effectively attenuated.

  More specifically, for example, when grinding n workpieces 50 (1) to 50-n, the grindstone position correction amount calculation means 65 calculates the workpieces 50 up to m (1 <m <n) sheets ( m) When the grinding process is finished, the position of the grinding operation surface 21a after finishing the first workpiece 50 (1) (the target grinding wheel position R (R = 0) shown in FIG. 4) The amount of deviation (= correction amount Ja) from the target grinding wheel position R) to the position of the grinding operation surface 21a after the completion of the processing of the m-th workpiece 50 (m) and the first workpiece 50 (1) are processed. To calculate the deviation (= correction amount Jb) from the target grindstone position R of the grinding operation surface 21b after the completion to the position of the grinding operation surface 21b after the completion of the machining of the m-th workpiece 50 (m) by calculation. belongs to.

  The grindstone position control means 68 is connected to the grindstone position correction amount calculation means 67 and the saddle driving devices 18a and 18b. The grindstone position control means 68 is based on the correction amounts Ja and Jb obtained by the grindstone position correction amount calculation means 67, based on the offset amount (the grinding operation surface of the cup-type grindstones 20a and 20b from the measurement positions of the spindle position sensors 120a and 120b). (The value obtained by adding the measured values of the spindle position sensors 120a and 120b to the distances to 21a and 21b), and the positions of the grinding operation surfaces 21a and 21b of the cup-type grindstones 20a and 20b with respect to the workpiece 50 are approximately The positions of the grinding operation surfaces 21a and 21b at the end of processing of the workpiece 50 (1) processed on the first sheet and the grinding operation surfaces 21a and 21b at the end of processing when processing other workpieces are the same. The position of the cup-type grindstones 20a and 20b is determined so that the positions are substantially the same. After the positions of the cup-type grindstones 20a and 20b are determined, grinding of the (m + 1) th workpiece 50 (m + 1) is started.

  Next, with reference to FIG. 9, the feedback process performed by the feedback means according to this embodiment of the present invention will be described. FIG. 9 is a control block diagram showing feedback processing according to this embodiment of the present invention. In FIG. 9, the same components as those shown in FIG.

  In the feedback processing, the position of the grinding operation surfaces 21a and 21b of the cup-type grindstones 20a and 20b at the end of the grinding of the first workpiece 50 (1) is set as the target grindstone position R (R = 0) and the third and subsequent sheets. Cup-type grindstones 20a and 20b based on the correction amounts Ja and Jb so that the positions of the grinding operation surfaces 21a and 21b at the end of grinding of the workpieces 50 (3) to 50 (n) become the target grindstone position R. This is done to control the position of. The position data of the grinding operation surfaces 21a and 21b at the end of grinding of the second workpiece 50 (2) is the same as the position data of the grinding operation surfaces 21a and 21b when grinding the third workpiece 50 (3). It is used when calculating the position correction amounts Ja and Jb.

  Next, the feedback method of the present embodiment will be described by taking as an example the case where n workpieces 50 (n) are ground.

  When the machining of the mth workpiece 50 (m) is completed, the processed surfaces 50a and 50b of the mth workpiece 50 (m) at the end of grinding are measured by the position sensors 45a and 45b, and the position data Ea− m, Eb-m are acquired, and components caused by the rotation period of the workpiece 50 generated by the rotation of the workpiece 50 having warpage and waviness are removed by the filters 61a, 61b, and the position data Eaf-m, Ebf- m is output.

  In the position data Eaf-m and Ebf-m, a stationary error component that does not originate from the rotation period of the workpiece 50 that is difficult to be attenuated by the filters 61a and 61b remains, and this stationary residual error component. Is caused by individual differences in the shape of the workpiece 50. When the position data Eaf-m and Ebf-m including such stationary remaining error components are input to the grindstone position estimation filter 83, the remaining stationary error components are reduced. The grindstone position estimation filter 83 has an influence of the measurement error d2 on the correction amounts Ja and Jb (the correction amount of the cup-type grindstone 20a is the correction amount Ja and the correction amount of the cup-type grindstone 20b is the correction amount Jb). It is for reducing.

  For the grindstone position estimation filter 83, for example, an observer filter such as a Kalman filter can be used. The grindstone wear amount calculation means 65 includes position data Eaf-m, Ebf-m with reduced noise components, position data Eaf-1, Ebf-1 and saddles 23a, 22b of the first workpiece 50 (1). Based on the position data Sa and Sb (position data of the grinding spindles 22a and 22b), the wear amount Uam (= Qa−Pa) of the cup-type grindstone 20a and the wear amount Ubm (= Qa + Pa) of the cup-type grindstone 20b are calculated. For each.

  The grindstone position correction amount calculation means 67 calculates correction amounts Ja and Jb for the cup-type grindstones 20a and 20b based on the wear amount Uam of the cup-type grindstone 20a and the wear amount Ubm of the cup-type grindstone 20b. At this time, it is possible to obtain correction amounts Ja and Jb in which the grinding wheel wear amount d1 mainly composed of the steady component and the low frequency component and the measurement error d2 mainly composed of the high frequency component are reduced. Based on the correction amounts Ja and Jb, the position of the cup-type grindstones 20a and 20b is controlled by the grindstone position control means 68 so as to become the target grindstone position R.

  By performing such feedback processing, the position of the cup-type grindstones 20a, 20b can always be set to the target grindstone position R, and the workpiece 50 can be moved without being affected by the wear amount of each cup-type grindstone 20a, 20b. It can be processed with high accuracy.

  Next, referring to the flowcharts shown in FIGS. 10 to 11, the double-head grinding apparatus 10 of the present embodiment implements the case where n workpieces 50 (1) to 50 (n) are machined as an example. The position correction processing of the grinding operation surfaces 21a and 20b of the pair of cup-type grindstones 20a and 20b will be described. 10 to 11 are flowcharts of this embodiment.

  When the process shown in FIG. 10 starts, first, the desired thickness W1 of the workpiece 50 after grinding is input to the grinding process end detection means 64 by the process of STEP101. In STEP 102, the pair of cup-type grindstones 20a and 20b rotate from the standby position, the grinding operation surfaces 21a and 21b come into contact with the first workpiece 50 (1), and the workpiece 50 (1) is ground. Is started.

  In the next STEP 103, the position sensors 45a and 45b detect the positions of the work surfaces 50a-1 and 50b-1 of the workpiece 50 (1) being ground, and the detected position data Ea-1 and Eb. −1 is transmitted to the filters 61a and 61b. In the filters 61a and 61b, data on the positions of the grinding operation surfaces 21a and 21b of the pair of cup-type grindstones 20a and 20b in which noise components due to the rotation period of the workpiece 50 are reduced are acquired from the position data.

  In STEP 104, it is determined whether or not the thickness W of the first workpiece 50 (1) being ground has reached a predetermined thickness W1. When a negative determination (No) is made in STEP 104, the process returns to STEP 103. When an affirmative determination is made (Yes), it is determined that the grinding of the first workpiece 50 (1) has been completed, and the process proceeds to STEP105.

  In STEP 105, the positions of the processing surfaces 50a, 50b of the first workpiece 50 (1) and the positions of the saddles 23a, 22b are detected. In STEP 106, the processing surface 50a of the first workpiece 50 (1). , 50b position data Eaf-1, Ebf-1 and saddles 23a, 22b position data Sa1, Sb1 are stored in the storage means 63.

  Subsequently, in STEP 107, it is determined whether or not the grinding of the n workpieces 50 (1) to 50 (n) set in the double-head grinding apparatus body 15 has been completed. In STEP 107, when an affirmative determination is made (Yes), it is determined that the grinding of the n workpieces 50 (1) to 50 (n) has been completed, and the processing ends. When a negative determination (No) is made, the process proceeds to STEP 107.

  In the next STEP 108, grinding of the mth workpiece 50 (m) is started. Note that m is a natural number (m = 2, 3, 4,...) Greater than 2, and m ≦ n.

  In the next STEP 109, the position sensors 45a and 45b detect the positions of the processed surfaces 50a-m and 50b-m of the m-th workpiece 50 (m) being ground, and the detected position data is It is transmitted to the filters 61a and 61b. In the filters 61a and 61b, grinding wheel wear amount data relating to the wear amount of the pair of cup-type grinding wheels 20a and 20b is acquired from the position data.

  Subsequently, in STEP 110, it is determined whether or not the thickness of the mth workpiece 50 (m) being ground has reached a predetermined thickness W1. When a negative determination (No) is made in STEP 110, the processing returns to STEP 109. When an affirmative determination (Yes) is made, it is determined that grinding of the m-th workpiece 50 (m) has been completed, and the process proceeds to STEP 91.

  In STEP 111, the positions of the work surfaces 50a-m, 50b-m of the m-th workpiece 50 (m) and the positions of the saddles 23a, 22b are detected. In STEP 112, the m-th workpiece 50 (m) The position data Eaf-m, Ebf-m of the processed surfaces 50a-m, 50b-m and the position data Sam, Sbm of the saddles 23a, 22b are stored in the storage means 63.

  Subsequently, in STEP 113, the position data Eaf-1, Ebf-1 of the processed surfaces 50a-1, 50b-1 of the first workpiece 50 (1) and the mth workpiece are calculated by the grindstone wear amount calculating means 65. Based on the position data Eaf-m, Ebf-m of the 50 (m) processed surfaces 50a-m, 50b-m and the position data Sa1, Sb1, Sam, Sbm of the saddles 23a, 23b, each cup type grindstone The wear amounts Uam and Ubm of 20a and 20b are calculated.

  In the next STEP 114, the grinding operation surfaces 21a and 20b of the cup-type grindstones 20a and 20b are applied to the workpieces 50 (3) to 50 (n) to be processed based on the wear amounts Uam and Ubm of the cup-type grindstones 20a and 20b. The correction amounts Ja and Jb of the position of the pair of cup-type grindstones 20a and 20b so that the position is the same as the grindstone target position R are obtained.

  In the next STEP 115, the saddle driving devices 18a and 18b are driven based on the correction amounts Ja and Jb, respectively, to adjust the positions of the grinding operation surfaces 21a and 21b provided on the cup-type grindstones 20a and 20b.

  Subsequently, in STEP 116, it is determined whether or not the grinding of the n workpieces 50 (1) to 50 (n) set in the double-head grinding apparatus body 15 has been completed. When a negative determination (No) is made in STEP 115, the process proceeds to STEP 109. In STEP 115, when an affirmative determination (Yes) is made, it is determined that the grinding of the n workpieces 50 (1) to 50 (n) has been completed, and the processing ends.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Deformation / change is possible. The workpiece holder 25 that holds the workpiece is not limited to the configuration of the present embodiment. The present invention can also be applied to a double-side polishing apparatus that performs double-side processing of a workpiece using an abrasive cloth.

  In the present invention, when adjusting the position of a pair of grindstones, grinding wheel uneven wear, warpage of a workpiece generated between the position of the workpiece (= estimated grindstone position) obtained by measurement and the actual grindstone position, In consideration of measurement errors caused by waviness, the present invention can be applied to a double-sided machining apparatus that can improve the machining accuracy of a workpiece.

It is the figure which showed the double-headed grinding apparatus which is one Example of this invention. It is the figure which looked at the workpiece holder shown in FIG. It is a figure for demonstrating the component contained in the position data acquired by the position sensor. It is a figure for demonstrating the calculation method of the abrasion loss of cup type grindstone 20a, 20b. It is the figure which showed the power spectrum of the grindstone wear amount. It is the figure which showed the transfer function (gain) from the abrasion amount of the grindstone which has the frequency characteristic shown in FIG. 5 to the grinding operation surface at the time of a process end. It is the figure which showed the power spectrum of the measurement error. FIG. 8 is a diagram showing a transfer function (gain) from a measurement error having the frequency characteristics shown in FIG. 7 to a grinding operation surface at the end of machining. It is the control block diagram which showed the feedback process by this Example of this invention. It is a flowchart (the 1) of a present Example. It is a flowchart (the 2) of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Double-head grinding device 15 Double-head grinding device main body 16a, 16b Grinding device 17 Base 18a, 18b Saddle drive device 20a, 20b Cup type grindstone 21a, 21b Grinding operation surface 22a, 22b Grinding spindle 23a, 23b Saddle 25 Work holder 26 Workpiece Cage frame 27 Roller drive unit 28 Drive motor 29, 34, 42 Rotating shaft 31, 36 Pulley 33 Drive roller unit 35, 43 Grooved roller 38 Drive belt 41 Support roller unit 45a, 45b Position sensor 46a, 46b Position Sensor body 47a, 47b Contact 50 Work 50a, 50b Work surface 60 Wear correction amount calculation means 61b, 61b Filter 62 Work thickness calculation means 63 Storage means 64 Grinding end detection means 65 Grinding wheel wear amount calculation means 67 Grinding wheel position correction amount Calculation means 68 Wheel position control means 80 Feedback control means 83 Wheel position estimation filter 120a, 120b Spindle position sensor 121 First correction means 122 Second correction means C Rotation center position Eaf1, Ebf1, Eafm, Ebfm Work position G Position data Curve g Measured value of the grinding operation surface of the cup-type grinding wheel at the end of grinding H Ideal machining surface position curve I Position of the grinding operation surface of the cup-type grinding stone before grinding Ka1, Kb1, Kam, Kbm Wheel thickness M1 Displacement amount Measured value M2 Displacement amount ideal value M3 Error Pa, Pb Deviation amount Sa1, Sb1, Sam, Sbm Feed position t1 Machining start time t2 Machining end time

Claims (9)

A pair of processing members for processing both surfaces of the workpiece supported by rotation;
A main shaft provided integrally with the processing member;
Grinding wheel position control means for controlling the position of the spindle;
A spindle position sensor for detecting the feed position of the spindle;
Two position sensors for acquiring position data of a surface to be processed of the workpiece each time the workpiece is processed;
Based on the target position of the workpiece surface of the workpiece at the end of machining, the position of the workpiece surface of the workpiece, and the displacement of the feed position of the spindle, the amount of wear generated on each workpiece is calculated. Wear correction amount calculating means for calculating a correction amount for correcting the processing end position of each processing member to the target position based on the wear amount,
A double-sided processing apparatus comprising a feedback means for feeding back the correction amount to the grindstone position control means. The double-sided processing apparatus according to claim 1, wherein the wear correction amount calculation unit includes a filter that removes a component caused by a rotation period of a workpiece included in the position data. The wear correction amount calculation means corrects a steady component and a fluctuation component, which are wear components generated by machining, and reflects them in the processing of the wear correction amount calculation means.
The correction due to a measurement error generated between the position of the workpiece surface of the workpiece detected by the two position sensors and the position of the workpiece surfaces of the pair of workpiece members at the end of machining of the workpiece. The double-sided processing apparatus according to claim 1, wherein an influence on the amount is reduced. The double-sided processing apparatus according to any one of claims 1 to 3, wherein the wear correction amount calculation means includes a grindstone position estimation filter that removes a component of the measurement error. The wear correction amount calculation means calculates a correction amount of the position of the machining surface of the pair of machining members at the end of machining so as to remove the steady component and the fluctuation component by a second order integral component. Item 5. The double-sided processing apparatus according to any one of Items 1 to 4. The wear correction amount calculating means calculates a correction amount of the position of the machining surface of the pair of machining members at the end of machining so as to remove the steady component and the fluctuation component by a second order integral component and a first order integral component. The double-sided processing apparatus according to any one of claims 1 to 5, wherein: The wear correction amount calculation means corrects the positions of the machining surfaces of the pair of machining members at the end of machining so as to remove the steady component and the fluctuation component by using a second order integral component, a first order integral component, and a proportional component. The double-sided processing apparatus according to claim 1, wherein an amount is calculated. The double-sided processing apparatus according to any one of claims 1 to 7, wherein the two position sensors are cylinder-type contact position sensors. The double-sided processing apparatus according to claim 1, wherein the two position sensors are non-contact sensors.

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