JP3651082B2 - Grinding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is provided with a truing tool that is relatively movable in a direction parallel to and orthogonal to the outer peripheral surface of a grinding wheel supported by a grinding wheel platform, and the truing tool is cut into the outer peripheral surface or end surface of the grinding wheel. The present invention relates to a grinding apparatus that performs the above.
[0002]
[Prior art]
Conventionally, after grinding a preset number of workpieces in a grinding machine, truing is performed to sharpen the grinding wheel layer. The present applicant has proposed a technique for controlling the cutting amount of a grinding wheel in truing in Japanese Patent Publication No. 6-6262.
[0003]
In this publication, the distance from the truing tool to the detection pin (hereinafter referred to as step data) is stored in advance, and the grinding wheel is brought into contact with the detection pin before truing, and then the truing amount (for correction) is added to the step data. A technique is disclosed in which the grinding wheel is moved to the truing tool side in consideration of the cutting amount of the cutting tool and truing is performed, and after the truing, the grinding wheel is again brought into contact with the detection pin to update the step data.
[0004]
According to this technique, in order to measure the contact position of the grinding wheel by contacting the detection pin before truing, it is possible to cut the desired amount of grinding wheel with respect to the truing tool based on the measurement position of the grinding wheel. Is possible. Also, before and after truing, the grinding wheel is brought into contact with the detection pin and the contact position is measured, so that the grinding wheel during truing can be measured, and thus the actual cutting amount for the grinding wheel can be obtained. The size data of the grinding wheel can be accurately updated based on the amount of insertion.
[0005]
[Problems to be solved by the invention]
In the above technique, the reduction amount of the grindstone width after truing is obtained from the difference in the grindstone end face position obtained by performing contact detection before and after truing. However, since the end face position of the grindstone is displaced in the moving direction of the table due to the thermal displacement of the machine (between the grindstone platform and the table) in addition to the grindstone wear generated during processing and truing, the end face position obtained by contact detection is The actual deviation is several μm.
[0006]
That is, if the change amount (decrease amount) of the grindstone width is due to grindstone wear, it can be corrected by the contact detection technique. However, thermal displacement occurs in addition to grinding wheel wear, and the amount of change in grinding wheel width (displacement of the end face position) due to this thermal displacement cannot be detected separately from the grinding wheel wear amount, so the actual grinding wheel width is managed accurately. I couldn't.
[0007]
Here, in the grinding apparatus, since processing is being performed while performing truing 100 times or more with one CBN grindstone, if an error of several μm occurs per truing, this is accumulated, and finally An error of several hundred μm may occur. Here, if there is a difference of several hundreds of μm between the grinding wheel width data and the actual grinding wheel width, there is a possibility that a grinding residue may be generated or a grinding allowance may be increased during grinding of the end face of the workpiece, resulting in grinding burn. .
[0008]
The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a grinding apparatus capable of always accurately managing the grindstone width.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the grinding apparatus according to claim 1, a truing tool is mounted on the table 14 that can be relatively moved in a direction parallel to and perpendicular to the outer peripheral surface of the grinding wheel 22 supported by the grinding wheel base 20. 44, the truing tool 44 is cut into the end face of the grinding wheel 22 by relative movement between the table 14 and the grindstone table 20, and the table 14 and the grindstone table 20 are moved relative to each other based on the grindstone width data. A grinding device that performs machining by cutting the workpiece end face F1 with a grinding wheel 22;
An end face detection member 50 disposed on the grindstone table 20 so as to detect contact with the machining end face of the workpiece;
Whetstone width data at a specified timing Of wheel width direction thermal displacement error Whetstone width correction means for correcting
The grinding wheel width correcting means is:
A cutting position storage means for storing a cutting position Z3 of the grinding wheel 22 at the time of workpiece end surface machining;
After the workpiece machining, contact position storage means for detecting the contact of the workpiece end surface F1 with the end surface detection member 50 and storing the contact position Z4;
Relative distance calculation means for calculating a relative distance Z00 between the grindstone end face and the end face detection member 50 based on the cut position Z3 stored in the cut position storage means and the contact position Z4 stored in the contact position storage means. ,
By relative distance calculation means During initial value setting processing A relative distance difference calculating means for calculating a difference Zs between the calculated relative distance Z0 and the currently calculated relative distance Z00;
The difference Ws between the value WL of the wheel width data corrected previously by the wheel width correcting means and the current wheel width W2 updated in accordance with the wheel correction cutting amount T1 ′ cut during truing. Grinding wheel width difference calculating means for calculating,
From the relative distance difference Zs calculated by the relative distance difference calculating means and the grindstone width difference Ws calculated by the grindstone width difference calculating means. Grinding wheel width direction thermal displacement error Error calculating means for calculating
Calculated by the error calculation means Grinding wheel width direction thermal displacement error And grinding wheel width data correcting means for correcting the wheel width data based on the above.
[0010]
The gist of the present invention is that the whetstone width correcting means corrects whetstone width data after truing.
[0011]
The gist of the present invention is that the whetstone width correcting means corrects the whetstone width data in the truing interval according to the first or second aspect.
[0012]
[Action]
When the grinding wheel width data is updated according to the grinding wheel correction cutting amount T1 that is cut during truing, the grinding wheel width data is updated based on not only the grinding wheel wear amount but also the thermal displacement amount during truing. There is an error between the actual grinding wheel dimensions.
[0013]
On the other hand, in the grinding apparatus of claim 1, the cutting position storage means stores the cutting position Z3 of the grinding wheel 22 at the time of machining the workpiece end face F1, and the contact position storage means performs the workpiece end face F1 after machining the workpiece. Is detected by the end face detection member 50, and the contact position Z4 is stored. Then, the relative distance calculation means calculates the relative distance Z00 between the grindstone end face and the end face detection member 50 based on the cutting position Z3 stored in the cutting position storage means and the contact position Z4 stored in the contact position storage means. To do. Thereafter, the relative distance difference calculating means is operated by the relative distance calculating means. During initial value setting processing The difference Zs (actual wear amount of the grindstone) between the calculated relative distance Z0 (initial value) and the currently calculated relative distance Z00 is calculated.
[0014]
The wheel width difference calculating means is updated in accordance with the wheel width data value WL (initial value) previously corrected by the wheel width correcting means and the grinding wheel correction cutting amount that has been cut during truing. A difference Ws from the grindstone width W2 (including not only the wear amount of the grindstone described above but also the thermal displacement during truing) is calculated. Then, the error calculating means calculates the difference between the relative distance difference Zs calculated by the relative distance difference calculating means and the grindstone width Ws calculated by the grindstone width difference calculating means. Grinding wheel width direction thermal displacement error Is calculated. Finally, the wheel width data correction means is calculated by the error calculation means. Grinding wheel width direction thermal displacement error Correct the wheel width data based on
[0015]
According to the grinding device of claim 1, heat Even if the end face of the grindstone by contact detection changes due to the displacement, the grindstone width data can be managed and updated according to the actual dimension of the grindstone width.
[0016]
When the grinding wheel width data is updated in accordance with the grinding wheel correction cutting amount that has been cut during truing, an error occurs with the actual grinding wheel width, and this error is accumulated every truing. On the other hand, in the grinding apparatus of claim 2, since the grindstone width correcting means corrects the grindstone width data after truing, it is possible to prevent the errors in the grindstone width data during truing from being accumulated.
[0017]
Also in the truing interval between truing, the grindstone width changes due to wear and thermal displacement of the grindstone. On the other hand, in the grinding apparatus according to the third aspect, since the grinding wheel width correcting means corrects the grinding wheel width data even in the truing interval, the workpiece can always be processed with high accuracy.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view of a cylindrical grinding machine 10 embodying a grinding apparatus according to one embodiment of the present invention. In FIG. 1, a table 14 is guided and supported on a bed 12 so as to be movable in the horizontal direction. A headstock 16 and a tailstock 18 are arranged on the table 14 so as to face each other, and a chuck 16 a for gripping one end of the work W is provided at one end of the headstock 16. A center 18a for supporting the other end of the center is provided. Both ends of the work W are supported by the headstock 16 and the tailstock 18 so that the work rotation axis is parallel to the moving direction of the table 14, and the work W is rotationally driven by the headstock 16. It has become.
[0019]
The table 14 is further provided with a contact detection device 30 for detecting the position of the grinding wheel 22 and a grinding wheel correcting device 40 for sharpening the grinding wheel 22. In the contact detection device 30, a first detection pin 34 a that faces the end face side of the grinding wheel 22 and a second detection pin 34 b that faces the outer peripheral side of the grinding wheel 22 protrude from the detection pin head 32. . The detection pin head 32 is supported on the table 14 side via an AE sensor 36 that detects a contact signal between the first detection pin 34 a and the second detection pin 34 b and the grinding wheel surfaces G 1 and G 2 of the grinding wheel 22. On the other hand, as shown in FIG. 2A, the grindstone correcting device 40 is configured by attaching a truing tool 44 to a truer shaft 42. The truing tool 44 includes a first modified grinding surface 44a for concentrating the first grinding wheel surface G1 of the grinding wheel 22, a second modified grinding surface 44c for concentrating the second grinding wheel surface G2, and a core 44b. It arrange | positions and it is comprised so that the truer axis | shaft 42 may be rotated by forward / reverse rotation by the built-in motor which is not shown in figure.
[0020]
On the other hand, on the bed 12, the grinding wheel base 20 is guided and supported in a horizontal direction orthogonal to the moving direction of the table 14, and the grinding wheel 22 can rotate around an axis parallel to the moving direction of the table 14. It is supported by. As shown in FIG. 2A, the grinding wheel 22 is constructed by attaching a grinding wheel layer 22b in which super hard CBN abrasive grains are bonded by vitrify bonding to the outer periphery of a thin disk 22a. Thus, it is rotated at an ultra high speed via a pulley and a belt (not shown). On the other hand, a touch sensor 50 is disposed at the end of the grindstone table 20 on the table 14 side. As shown in FIG. 3B, the touch sensor 50 includes a feeler 54 for detecting a position in contact with the machining end surface F1 of the workpiece W, and a measurement head 52 for supporting the feeler 54, and grinding. In order to avoid contact with other members, the revolving motor 56 is retracted to a position indicated by a dotted line in the drawing. The touch sensor 50 is configured to send an end face measurement signal to the numerical controller 100 side when detecting contact with the processing end face F1 of the workpiece W.
[0021]
Next, the configuration of the numerical controller 100 that controls the cylindrical grinding machine 10 will be described. The numerical controller 100 mainly includes a central controller 102 that manages the entire apparatus, a memory 108 that holds various control values and programs, and interfaces 104 and 106. The memory 108 stores a grinding program, a grindstone correction program, a grindstone width correction program, grindstone diameter / grindstone width data, and distance data between the grindstone end face G1 and the feeler 54. Various data are input to the numerical control device 100 via the input device 110. The input device 110 includes a keyboard for inputting data and the like, and a display device such as a CRT for displaying data. In addition, a contact signal from the contact detection device 30 is input to the numerical control device 100 via the amplifier 120. The amplifier 120 is configured to output an on / off signal to the numerical controller 100 according to a detection signal from the contact detection device 30.
[0022]
The numerical controller 100 sends a drive signal via a first motor drive circuit 80 to a first servo motor 82 for sending the grinding wheel base 20 in a horizontal direction orthogonal to the moving direction of the table 14 by a ball screw (not shown). give. The first encoder 84 attached to the first servo motor 82 sends the rotational position of the first servo motor 82, that is, the position of the grinding wheel base 20 to the first motor drive circuit 80 and the numerical controller 100 side. It is configured. On the other hand, the numerical controller 100 gives a drive signal via a second motor drive circuit 90 to a second servo motor 92 for feeding the table 14 in the horizontal direction by a ball screw (not shown). The second encoder 94 attached to the second servo motor 92 is configured to send the position of the table 14 to the second motor drive circuit 90 and the numerical controller 100.
[0023]
When the grinding wheel 22 is replaced with a new one, the cylindrical grinding machine 10 starts machining after performing runout. Then, when a predetermined number of workpieces are machined and it becomes necessary to correct the grinding wheel surface of the grinding wheel 22, truing is performed, and the truing and workpiece machining are repeated. Further, in the cylindrical grinding machine 10 of this embodiment, as will be described later, the grinding wheel width is corrected at the truing interval, and the grinding wheel width data is updated to always proceed the processing based on the accurate grinding wheel width data. Processing operations by the cylindrical grinding machine 10 will be described with reference to explanatory diagrams of FIGS. 2, 3, and 4 and flowcharts of FIGS. 5 to 10 showing processing by the numerical controller 100.
[0024]
The numerical controller 100 first determines whether the grinding wheel 22 has been replaced (S100 shown in FIG. 5). When the grinding wheel 22 is replaced (Yes in S100), the grinding wheel end face position and the like are measured using a master plate (not shown), and grinding wheel shape data such as the grinding wheel width is stored (S101). Thereafter, the grinding wheel 22 is shaken (S102). Here, the run-out refers to a portion that is not a perfect circle centering on the grindstone axis on the outer peripheral surface of the grindstone. When the grindstone is attached to the grindstone shaft (not shown), a runout of several hundred μm occurs. ing. For this reason, in the same way as the operation at the time of truing to be described later, cutting is performed in several tens of times with a truing tool, and the surface of the grindstone is peeled off to remove runout.
[0025]
Then, the numerical controller 100 starts truing (S103). This truing is performed continuously with the above-described run-out cycle. The truing process will be described in detail with reference to the flowchart of FIG. 8 showing the subroutine of the process and FIG. 2 showing the operation at this time.
[0026]
First, the numerical controller 100 shown in FIG. 1 controls the first servo motor 82 to send the grinding wheel base 20 to the table 14 side, and the first grinding wheel surface (end surface) of the grinding wheel 22 to the side of the first detection pin 34a. Side) After positioning G1, the second servo motor 92 is controlled to move the table 14 horizontally, thereby sending the detection pin 34a to the grinding wheel 22 side as shown in FIG. 1 grinding wheel surface contact feed: S400). This contact feed is continued until a contact signal is detected (S401 is No). When the contact between the first detection pin 34a and the first grinding wheel surface G1 of the grinding wheel 22 is detected by the AE sensor 36 and the contact signal is input through the amplifier 120 (S401 is Yes), the table 14 And the contact position coordinate Zb of the first grindstone surface G1 is stored (S402). Then, the table 14 moves backward to the left by a predetermined amount in FIG. 1, the first grindstone surface G1 moves away from the first detection pin 34a, and the grindstone base 20 moves backward by a predetermined amount.
[0027]
Next, in order to measure the amount of wear that has occurred during machining, the contact position coordinate Za when the measurement is performed before being stored in the memory 108 from the contact position coordinate Zb of the first grindstone surface G1 measured this time. Is subtracted to calculate the amount of change (Zb-Za) of the first grinding wheel surface G1 position, and this value is stored (S403). Then, the grinding wheel width W obtained by subtracting the amount of change (Zb−Za) from the grinding wheel width W 0 stored in the memory 108. 2 The grindstone width data is updated to (= W0− (Zb−Za)) (S404). Here, since the machining is started, the amount of change (Zb−Za) is zero.
[0028]
Thereafter, a value T1 (correction) for cutting the first grinding wheel surface G1 of the grinding wheel 22 into a relative distance (step data) H0 between the first detection pin 34a and the first correction grinding surface 44a with reference to the contact position coordinate Zb. The amount of movement (H0 + T1) between the grinding wheel 22 and the truing tool 44 based on the contact position coordinate Zb is calculated (S405). Then, the grinding wheel 22 is moved relative to the truing tool 44 as shown in FIG. 2B by the movement amount obtained by adding the retraction amount of the first detection pin 34a with respect to the first grinding wheel surface G1 to the calculated movement amount (H0 + T1). The first grindstone surface G1 is positioned at the grindstone correction start position facing the first correction grinding surface 44a of the truing tool 44. Then, the grinding wheel base 20 is advanced, and the first grinding wheel surface G1 of the grinding wheel 22 is trued with the first corrected grinding surface 44a (S406).
The correction cutting amount T1 may be divided into a plurality, and the correction cutting amount of the table 14 and the correction feed of the grindstone table 20 may be performed a plurality of times. When the correction of the first grindstone surface G1 is finished, the table 14 moves backward by a predetermined amount in FIG. 1, the first grindstone surface G1 moves away from the first corrected grinding surface 44a, and the grindstone table 20 moves backward by a predetermined amount.
[0029]
Thereafter, in steps 407 and 408, the truing wheel 22 is detected for contact in the same manner as in steps 400 and 401 described above, and the corrected first grinding wheel surface G1 is corrected as shown in FIG. The contact position Zc is detected by the first detection pin 34a. Then, the corrected contact position coordinate Zc of the first grindstone surface G1 is stored in the memory 108 (S409).
[0030]
After that, the numerical controller 100 calculates an actual grinding wheel width reduction amount T1 ′ (amount of change in the first grinding wheel surface G1) due to wear of the truing tool 44 by truing (S410). Here, the actual correction cut amount T1 ′ is calculated by subtracting the contact position coordinate Zb before truing from the current contact position coordinate Zc (T1 ′ = Zc−Zb).
[0031]
Subsequently, the numerical controller 100 updates the grindstone width based on the actual decrease amount T1 ′ of the grindstone width (S411). That is, the grindstone width is replaced with a value W2 (= W1−T1 ′) obtained by subtracting the decrease T1 ′ from the grindstone width W1 before truing. Thereafter, the wear amount ΔT (= T1−T1 ′) of the first corrected grindstone surface 44a is calculated by subtracting the decrease amount T1 ′ from the corrected cut amount T1 obtained by performing the cut amount (S412). Finally, based on the wear amount ΔT of the first corrected grinding wheel surface 44a, the step data H0 before truing is corrected to the step data H1 after truing (= H0−ΔT) (S413), and the first grinding wheel surface The truing process for G1 is terminated.
[0032]
Subsequently, truing by contact detection is similarly performed on the second grindstone surface G2. In FIG. 2A, RO is a grindstone diameter stored before contact detection, and J0 is a relative distance (step data) between the second detection pin 34b and the second grinding surface 44c. R0 and step data J0 are updated as needed. As described above, all the steps of the truing process are completed.
[0033]
The description will be continued again with reference to the flowchart of FIG. 5 showing the main operation. When the truing process in step 103 is completed, the numerical controller 100 resets the variable C indicating the number of machining after truing (S104), and resets the variable D indicating the number of machining after the grinding wheel width correction (S105). ), 1 is set to an initial value setting flag for proceeding with an initial value setting process described later (S107).
[0034]
Thereafter, the workpiece W is loaded and set between the head stock 16 and the tailstock 18 on the table 14 shown in FIG. 1 (S108 shown in FIG. 6). Then, it is determined whether to perform truing based on whether or not the variable C indicating the number of machining after truing exceeds a predetermined number C1 (here, 100) (S109). Here, since processing is to be started, the determination in step 109 is No, and the process proceeds to step 113.
[0035]
In step 113, based on the grinding wheel width data W2 and grinding wheel diameter data updated and stored in the memory 108, as shown in FIG. 3A, the grinding wheel 22 is pressed perpendicularly to the workpiece W to grind the end face F2. Subsequently, the grinding wheel is traversed from the end surface F2 toward the end surface F1, and the cylindrical portion Wg of the workpiece W is processed. And the position coordinate Z1 at the time of workpiece | work end surface F1 process is memorize | stored (S114). Thereafter, 1 is added to the variable C indicating the number of machining after truing (S115), and 1 is added to the variable D indicating the number of machining after the grinding wheel width correction (S116).
[0036]
Subsequently, the numerical controller 100 determines whether or not the initial value setting flag is set (S117 shown in FIG. 7). Here, since the initial value setting flag is set in step 107 (Yes in S117), the initial value setting process is started (S118). The initial value setting process will be described with reference to the flowchart of FIG. 9 showing a subroutine of the process.
[0037]
First, the current stored in the memory 108 (That is, when the first truing is completed after the grinding wheel replacement) The grinding wheel width W2 of the grinding wheel 22 is stored as initial value data WL (S200). Then, as shown in FIG. 3B, the touch sensor 50 is sent to the machining end face F1 of the workpiece W, the feeler 54 is brought into contact, and the position coordinate Z2 when the end face measurement signal from the touch sensor 50 is turned on is stored. (S201). Subsequently, the position coordinate Z2 when the end face measurement signal is turned on is subtracted from the position coordinate Z1 of the work end face when the first work is processed in step 113 (see FIG. 3A). 3C, a distance Z0 (= Z1-Z2) from the first grinding wheel surface G1 of the grinding wheel 22 to the feeler 54 is calculated, and this value Z0 is calculated from the first grinding wheel surface G1 to the feeler 54. Is stored in the memory 108 as an initial value of the distance to (S202). Then, the initial value setting flag is reset to 0 (S203), thereby completing the initial value setting process.
[0038]
Subsequently, the numerical controller 100 determines whether or not to correct the grindstone width (S119 shown in FIG. 7). That is, it is determined whether or not the machining number D after grinding wheel width correction, which will be described later, exceeds a predetermined number D1 (here, 20), and if it exceeds this predetermined number D1 (S119). Yes), the grindstone width is corrected in the truing interval (from the truing to the next truing) (S121). Here, since the first workpiece has been processed (No in S119), it is determined whether the truing flag indicating that truing has been performed is set (S120), but the truing flag is set. Since there is not (S120 is No), the workpiece W which has been processed is unloaded (S122), and it is determined whether the processing has been completed for all the workpieces W (S123). Here, since the machining has not been completed (No in S123), the process returns to step 100 shown in FIG.
[0039]
In step 100, it is determined whether or not the grinding wheel 22 has been replaced. Here, however, it is determined whether the determination in step 100 is No and an instruction to reset the initial value is given (S106). Here, when the initial value setting is instructed other than when the grinding wheel is exchanged, the corresponding step 106 becomes Yes, and the process proceeds to step 107 to set the initial value setting flag to 1. Proceeding to the initial value setting process (S118) described above, the initial value is reset. On the other hand, when the initial value setting is not instructed (No in S106), the workpiece is loaded (S108 shown in FIG. 6), and machining for the next workpiece is started. For each workpiece machining, the coordinate Z3 of the measurement end face F1 of the workpiece W in S114 is always stored.
[0040]
Here, the machining of the workpiece W is repeated, and if the machining number D exceeds a preset number D1 (20), that is, step 119 becomes Yes at the 21st machining, and a grindstone width correction process (S121 described later) is performed. The processing number D is cleared by the end of the grinding wheel width correction process (S306 shown in FIG. 10). The grindstone width correction process is repeated for every 20 processing lines (that is, 41st, 61st, 81st).
[0041]
When the number of workpieces C processed becomes the 101st and exceeds the predetermined number C1 (100), the determination of C> C1 in step 109 shown in FIG. 6 becomes Yes, and the truing process is started. (S110), the grinding stone is sharpened by truing in the same manner as in FIG. 2 and FIG. Upon completion of the truing process (S110), the value of the variable C indicating the number of machinings after truing is reset (S111), and a truing flag for performing a grindstone width correcting process (to be described later) subsequent to truing is set to 1. (S112). Here, after completion of the truing process (S110), it is updated to the grindstone width W2 (different from the dimension W2 used in the initial value setting process).
[0042]
Thereafter, the carried workpiece (101st) is machined (S113), and the coordinate Z3 of the measurement end face F1 of the machined workpiece W is stored (S114). Then, through the processing from step 115 to step 119, it is determined whether or not the truing flag is set (S120 shown in FIG. 7). Here, since the truing flag is set in step 112 above (S120 is Yes), the grindstone width correction process is started (S121).
[0043]
The grindstone width correction process in step 121 will be described with reference to FIG. 10 showing a subroutine of the process. First, similarly to step 201 described above with reference to FIG. 3B, the touch sensor 50 is sent to the machining end face F1 of the workpiece W, the feeler 54 is brought into contact, and the end face measurement signal from the touch sensor 50 is turned on. The position coordinate Z4 is stored (S300). Subsequently, the position coordinate Z4 when the end face measurement signal is turned on from the position coordinate Z3 (see FIG. 3A) of the workpiece machining end face when machining the 101st workpiece stored in step 114. To calculate the distance Z00 (= Z3-Z4) from the first grinding wheel surface G1 of the grinding wheel 22 to the feeler 54 (see FIG. 3C) and store it in the memory 108 (S301). . The calculated distance Z00 And the difference between the distance Z0 Error such as thermal displacement Almost Not included.
[0044]
Then, by subtracting the current distance Z00 from the initial value Z0 of the distance measured in the initial value setting process, the difference Zs (= Z0−) between the initial value, which is the actual wheel width reduction amount at the present time, and the current value. Z00) is calculated (S302). Next, the difference between the initial wheel width WL stored in the memory 108 and the current wheel width W2 updated for each truing and stored in the memory 108, that is, the wheel width reduction amount Ws ( = WL-W2) is calculated. Then, it is determined whether the above-described actual grinding wheel width reduction amount Zs (= Z0−Z00) is equal to the grinding wheel width reduction amount Ws on the data (S304). Here, when both the reduction amounts Zs and Ws are equal (S304 is Yes), an error due to thermal displacement has not occurred, and the current wheel width currently stored in the memory 108 is correct. The process proceeds to step 306 without correction. On the other hand, when the reduction amounts Zs and Ws are different (No in S304), the grinding wheel width data is corrected (S305).
[0045]
The processing in step 305 will be described with reference to FIG. As shown in FIG. 4A, when the actual grindstone width W2 ′ is larger than the grindstone width W2 stored in the memory 108 (CNC data), the distance initial value Z0 between the grindstone end surface and the feeler 54, and the current The difference Zs (= Z0−Z00) between the wheel end face of the wheel and the feeler 54 is smaller than the wheel width reduction amount Ws (= WL−W2) of CNC data [Zs (= Z0−Z00) <Ws. (WL-W2)].
In this case, the grinding wheel width data is corrected by replacing the grinding wheel width data with the actual grinding wheel width W2 ′ obtained by the following equation.
[Expression 1]
W2 '= W2-{(Z0-Z00)-(WL-W2)}
W2 '= W2- (Zs-Ws)
[0046]
Further, as shown in FIG. 4B, when the actual grinding wheel width W2 ′ is smaller than the grinding wheel width W2 of the CNC data [Zs (= Z0−Z00)> Ws (= WL−W2)]. Also in this case, the grindstone width data is corrected by replacing the grindstone width data with the actual grindstone width W2 ′ obtained by the following equation exactly equal to the above equation (1).
[Expression 2]
W2 '= W2-{(Z0-Z00)-(WL-W2)}
W2 '= W2- (Zs-Ws)
[0047]
By this correction, it is possible to remove the relative shift (error) caused by the thermal displacement in the moving direction of the table 14 generated between the table 14 and the grindstone table 20, and it is possible to prevent the errors from accumulating every truing. Then, by resetting the variable D indicating the machining number after truing (S306) and resetting the truing flag to 0 (S307), the grinding wheel width correcting process is terminated, and the process proceeds to step 122 shown in FIG. The workpiece W that has been processed is unloaded, and the processing is continued thereafter.
[0048]
This numerical control apparatus 100 corrects the above-mentioned grindstone width correction for the 121st, 141st, 161st, and 181st lines after the end of truing during the 101st workpiece machining until the next truing during the 201st workpiece machining. Processing (S118) is performed. As a result, when it is assumed that there is a large amount of change in the wheel width due to wheel wear and thermal displacement during the truing interval (for example, when the number of workpieces processed is large), the error when updating the wheel width data after truing is reduced. It is possible to prevent occurrence of defective products in the first processing after truing.
[0049]
In this embodiment, the cycle time is long because the grinding wheel width correction process is performed in the truing interval in the machining cycle. For this reason, when it is determined that the grinding wheel wear amount and the thermal displacement amount are small during the truing interval, the grinding wheel width correction process in the truing interval can be omitted. This can be realized by setting the variable D1 and the variable C1 equal.
In the above, truing by contact detection is used for the truing process, but the present invention can also be applied to truing by direct detection.
[0050]
Next, a second embodiment of the present invention using direct detection for truing will be described with reference to FIGS. In the description of the second embodiment, illustration and description of the same members as in the first embodiment are omitted. In the second embodiment, the contact of the grinding wheel 22 with the truing tool 44 is directly detected (direct detection) by an AE sensor (not shown) attached to the grinding wheel 22 or the truing tool 44, and the contact position thereof. Is stored, and the grinding wheel 22 is cut into the truing tool 44 by a corrected cutting amount with reference to the contact position.
[0051]
The numerical controller 100 shown in FIG. 1 stores in the memory 108 a grinding wheel diameter R0 (see FIG. 11A), a contact position coordinate Zd between the current truing tool 44 and the grinding wheel 22, and a current grinding wheel width W0. Is remembered. First, the numerical controller 100 controls the first servo motor 82 to send the grinding wheel base 20 to the table 14 side, and the first grinding wheel surface G1 of the grinding wheel 22 to the side of the first correction grinding surface 44a of the truing tool 44. Then, the second servo motor 92 is controlled to move the table 14 horizontally (S500), and this contact feed is continued until a contact signal is detected (No in S501). Then, as shown in FIG. 11B, a contact signal between the first corrected grinding surface 44a of the truing tool 44 and the first grinding wheel surface (end surface side) G1 of the grinding wheel 22 is detected by an AE sensor (not shown), and the amplifier When a contact signal is input via 120 (Yes in S501), the contact position coordinate Ze of the first grindstone surface G1 is stored (S502).
Then, the table 14 is moved backward to the left by a desired amount in FIG. 1, the first grindstone surface G1 is separated from the first corrected grinding surface 44a, and the grindstone base 20 is retracted by a predetermined amount.
[0052]
Next, in order to measure the amount of wear that has occurred during machining, the contact position coordinate Zd of the first grinding wheel surface G1 measured this time is stored in the memory 108 before the measurement is performed. By subtracting, the change amount (Ze−Zd) of the first grindstone surface G1 position is calculated, and this value is stored (S503). Then, the wheel width data is updated to the wheel width W1 (= W0− (Ze−Zd)) obtained by subtracting the change amount (Ze−Zd) from the wheel width W0 stored in the memory 108 (S504).
[0053]
Thereafter, the retraction amount of the first correction grinding surface 44a with respect to the first grinding wheel surface G1 is added to the value T1 (correction cutting amount) for cutting the first grinding wheel surface G1 of the grinding wheel 22 based on the contact position coordinate Ze. As shown in FIG. 11C, the grinding wheel 22 is sent to the first correction grinding wheel surface 44a side by the amount of movement, and the first grinding wheel surface G1 faces the first correction grinding surface 44a of the truing tool 44. Position it at the position Zf (= Ze−T1). And the grindstone base 20 is advanced, and the truing of the 1st grindstone surface G1 is performed (S505). Thereafter, the grindstone width W0 is updated to W2 (= W1-T1) based on the corrected cutting amount T1 (S506). Thereby, the truing process with respect to the 1st grindstone surface G1 is completed.
[0054]
Subsequently, truing by direct detection is similarly performed on the second grindstone surface G2, and the grindstone diameter R0 is updated.
As described above, the entire process of the truing process is completed.
In the truing process based on the direct detection in which the grinding wheel dimension data is updated as described above, there is an advantage that the truing tool 44 can accurately cut the grinding wheel by a desired correction cutting amount. When the truing tool 44 is worn at the time, there is a problem that the grinding wheel dimension data cannot be managed accurately. Further, when an error due to thermal displacement is added, the grindstone dimension data cannot be managed accurately.
[0055]
However, by performing the grindstone width correction process of the present invention shown in FIG. 10 after the truing process, the actual grindstone width dimension can be reliably corrected.
In other words, the current wheel width data stored in the memory 108 is corrected by the difference between the wheel width reduction amount and the wheel width reduction amount in the data, so that the wheel width data stored in the memory 108 is corrected. Even if a plurality of errors are included, all of them are eliminated, and the grindstone width dimension can be reliably managed to the actual grindstone width dimension.
[0056]
In both the first and second embodiments described above, the wheel width data can be accurately managed to the actual size of the wheel width even if the wheel end face by contact detection changes due to the wheel wear and thermal displacement. A width dimension K1 from the end face F2 to the end face F1 can be secured in the machining of the cylindrical portion Wg of the workpiece W shown. The grinding wheel diameter data can be corrected and managed by using a known outer diameter sizing in the processing of the cylindrical portion Wg of the workpiece W.
[0057]
In the embodiment described above, an example in which CBN is used for the grindstone has been described, but it goes without saying that the truing device for the grindstone of the present invention can also be applied to the case of using a normal grindstone.
[0058]
【effect】
As described above, according to the first aspect of the present invention, even if the grindstone end face is changed by contact detection due to grindstone wear and thermal displacement, the grindstone width data can be managed and updated according to the actual size of the grindstone width. For this reason, it becomes possible to improve processing accuracy.
[0059]
In the invention of claim 2, since the wheel width data is corrected after truing, errors in the wheel width data during truing can be prevented from accumulating. In addition, it is possible to prevent unburned parts during end surface grinding and workpiece burning due to an increase in machining allowance. Further, by grasping the reduction amount of the grindstone width, the life of the grindstone can be accurately determined, and the grindstone can be effectively used.
[0060]
In the invention of claim 3, since the grindstone width data is corrected even in the truing interval, the workpiece can always be machined with high accuracy.
[Brief description of the drawings]
FIG. 1 is a plan view of a cylindrical grinding machine according to a first embodiment of the present invention.
FIG. 2 is an explanatory view showing a truing operation by the cylindrical grinder shown in FIG.
FIG. 3 is an explanatory view showing a contact detection operation of a workpiece end face by the cylindrical grinding machine shown in FIG. 1;
4 is an explanatory view showing the distance between the workpiece end surface and the feeler 54 by the cylindrical grinding machine shown in FIG. 1; FIG.
FIG. 5 is a flowchart of a main operation by a numerical controller that controls a cylindrical grinder.
FIG. 6 is a flowchart of a main operation by a numerical controller that controls a cylindrical grinder.
FIG. 7 is a flowchart of a main operation by a numerical controller that controls a cylindrical grinder.
FIG. 8 is a flowchart showing a subroutine of a truing operation by the numerical controller.
FIG. 9 is a flowchart showing a subroutine of initial value setting processing by the numerical controller.
FIG. 10 is a flowchart showing a subroutine of grinding wheel width correction processing by the numerical controller.
FIG. 11 is an explanatory view showing a truing operation by the cylindrical grinder according to the second embodiment of the present invention.
FIG. 12 is a flowchart showing a subroutine of a truing operation by the numerical control apparatus according to the second embodiment of the present invention.
[Explanation of symbols]
10 Cylindrical grinding machine
14 tables
20 Whetstone stand
22 Grinding wheel
30 Contact detection device
40 Grinding wheel correction device
44 Truing tools
50 touch sensor
54 Feeler
100 Numerical controller

Claims (3)

Comprising a relatively movable truing tool on the outer circumferential surface in a direction parallel and a direction perpendicular thereto of the grinding wheel supported grinding wheel table, performs a truing by cutting the truing tool on the end face of the grinding wheel, and a table A grinding device that performs processing by moving the grinding wheel table relative to the grinding wheel width data and cutting a workpiece end surface with the grinding wheel,
An end face detection member disposed on the grindstone platform so as to be able to detect contact with the machining end face of the workpiece;
And a grinding wheel width correction means for correcting the grinding wheel width direction thermal displacement error of the grindstone width data at a predetermined timing,
The grinding wheel width correcting means is:
A cutting position storage means for storing the cut position of the grinding wheel at the work end face machining,
After the workpiece processing, contact position storage means for detecting the contact of the workpiece end surface with the end surface detection member and storing the contact position;
Relative distance calculation means for calculating a relative distance between the grindstone end face and the end face detection member based on the cut position stored in the cut position storage means and the contact position stored in the contact position storage means;
A relative distance difference calculating means for calculating a difference between the relative distance calculated in the initial value setting process by the relative distance calculating means and the currently calculated relative distance;
Wheel width difference that calculates the difference between the value of the wheel width data previously corrected by the wheel width correcting means and the current wheel width updated in accordance with the grinding wheel correction cutting amount that was cut during truing A calculation means;
An error calculation means for calculating a thermal displacement error in the grinding wheel width direction from a difference in relative distance calculated by the relative distance difference calculation means and a difference in grinding wheel width calculated by the grinding wheel width difference calculation means;
A grinding apparatus comprising: grinding wheel width data correcting means for correcting the grinding wheel width data based on the thermal displacement error in the grinding wheel width direction calculated by the error calculating means.   2. The grinding apparatus according to claim 1, wherein the grinding wheel width correcting means corrects the grinding wheel width data after truing.   The grinding apparatus according to claim 1 or 2, wherein the grinding wheel width correcting means corrects the grinding wheel width data in a truing interval.

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