JP5991134B2 - Grinding machine and method for calculating rigidity of workpiece in grinding machine - Google Patents

Description

  The present invention relates to a grinding machine for calculating the rigidity of a workpiece and a method for calculating the rigidity of a workpiece in the grinding machine.

  In the grinding process, by grasping the rigidity of the workpiece, the machining accuracy can be improved. Therefore, as a method for calculating the rigidity of the workpiece, there are methods described in Patent Documents 1 and 2. In Patent Document 1, when a predetermined load is applied to a workpiece by a pressing device, the bending amount of the workpiece is measured to calculate the rigidity of the workpiece based on the predetermined load and the bending amount. Is described.

  In Patent Document 2, the position of the grinding wheel platform during grinding and the grinding resistance and the position of the grinding wheel platform when the grinding wheel is in contact with the workpiece when the amount of bending of the workpiece is zero are described. The calculation of stiffness is described.

JP-A-11-90800 JP 2008-93787 A

  However, since the method described in Patent Document 1 requires a dedicated pressing device, the cost is increased. In the method described in Patent Document 2, it is not easy to realize the moment when the amount of bending of the workpiece is zero and the grinding wheel contacts the workpiece. Therefore, it is impossible to calculate the rigidity of the workpiece with high accuracy.

  The present invention has been made in view of such circumstances, a grinding machine capable of using measurement information during grinding without using a dedicated device, and capable of calculating the rigidity of a workpiece with higher accuracy. An object of the present invention is to provide a method for calculating the rigidity of a workpiece in a grinding machine.

(Grinder)
(Claim 1) The grinding machine according to the present means, in each of a plurality of states in which the amount of bending of the workpiece is changed by changing the flow rate of the grinding fluid supplied to the grinding point of the workpiece, the position of the grinding wheel, Measuring means for measuring the diameter of the workpiece and the pressing force against the workpiece by the grinding wheel, and stiffness calculation means for calculating the rigidity of the workpiece based on the measured position, diameter and pressing force.

(Claim 2) Preferably, the measuring means is in a spark-out state, and a plurality of states in which the amount of bending of the workpiece is changed by changing the flow rate of the grinding fluid supplied to the grinding point of the workpiece. In each of the above, the position, diameter and pressing force are measured.
(Claim 3) Preferably, the workpiece has an eccentric or non-circular shape, the measuring means measures the position, diameter and pressing force according to the phase of the workpiece, and the rigidity calculating means The rigidity according to the phase of the workpiece is calculated.

  (Claim 4) Preferably, in the first measurement, the position, the diameter, and the pressing force are measured in a state where the workpiece is bent with the flow rate of the grinding fluid supplied to the grinding point of the workpiece as the first flow rate. In the second measurement, the flow rate of the grinding fluid supplied to the grinding point of the workpiece is different from the first flow rate after performing the back-off operation after the first measurement and releasing the bending amount of the workpiece. Measurement of the position, diameter, and pressing force in a state where the workpiece is bent again as the second flow rate, the measuring means performs each of the first measurement and the second measurement, and the rigidity calculating means is the first measurement. The rigidity of the workpiece is calculated based on the position, diameter, and pressing force measured in each of the second measurement and the second measurement.

  (Claim 5) When the back-off operation is performed as described above, the second flow rate may be smaller than the first flow rate.

  (Claim 6) Preferably, in the first measurement, the position, the diameter, and the pressing force are measured in a state where the workpiece is bent with the flow rate of the grinding fluid supplied to the grinding point of the workpiece as the first flow rate. The second measurement is a state in which the flow rate of the grinding fluid supplied to the grinding point of the workpiece is set to a second flow rate lower than the first flow rate while continuing the state where the workpiece is bent from the state of the first measurement. , Measurement of the position, diameter and pressing force, the measuring means performs each of the first measurement and the second measurement, the rigidity calculation means is measured in each of the first measurement and the second measurement The rigidity of the workpiece is calculated based on the position, diameter and pressing force.

  (Claim 7) Further, when the measurement is performed by any of the first measurement and the second measurement, the first measurement is performed in the rough grinding process, and the second measurement is performed in the finish grinding process. You may do it.

(Workpiece rigidity calculation method)
(Claim 8) Further, the method for calculating the rigidity of the workpiece in the grinding machine according to the present means includes a plurality of states in which the amount of bending of the workpiece is changed by changing the flow rate of the grinding fluid supplied to the grinding point of the workpiece. In each of the above, a measuring step for measuring the position of the grinding wheel, the diameter of the workpiece and the pressing force of the grinding wheel against the workpiece, respectively, and the rigidity of the workpiece based on each of the measured position, diameter and pressing force And a rigidity calculating step for calculating.
Moreover, about the preferable aspect in the said grinding machine, it can apply similarly to the said rigidity calculation method.

  (Claims 1 and 8) According to the present means, the position and pressing force of the grinding wheel are measured in a plurality of states where the flow rates of the grinding fluid are different. Here, the amount of bending of the workpiece differs because the flow rate of the grinding fluid is different. That is, the amount of bending of the workpiece when a plurality of different pressing forces are applied can be measured by the above measurement. Then, the rigidity of the workpiece can be obtained by dividing the difference in pressing force by the difference in deflection amount according to the Hooke's law.

  Therefore, the rigidity of the workpiece can be calculated without using a dedicated device. Moreover, all the several states to measure will be in the state which bent the workpiece. Each piece of information measured in a state where the workpiece is bent is a highly accurate value. Therefore, the rigidity of the obtained workpiece is a highly accurate value.

(Claim 2) Each information in a stable state can be measured by measuring each information in a spark-out state. Therefore, the rigidity of the workpiece can be calculated with high accuracy.
(Claim 3) An eccentric or non-circular workpiece may have different rigidity depending on the phase of the grinding point. Therefore, by performing measurement according to the phase of the workpiece, the rigidity according to the phase can be calculated based on the measurement result.

  (Claim 4) When the back-off operation is performed to release the bending amount of the workpiece, the flow rate of the grinding fluid is changed. That is, it is not during grinding that the amount of bending of the workpiece changes as the flow rate of the grinding fluid changes. Therefore, the flow rate change of the grinding fluid does not affect the machining accuracy of the workpiece.

  (Claim 5) Generally, the more the post-process, the higher the grinding accuracy of the workpiece. Also, the greater the grinding fluid flow rate, the greater the impact on the workpiece grinding accuracy. That is, by making the second flow rate smaller than the first flow rate, the grinding accuracy of the workpiece can be prevented from being affected by the grinding fluid as in the subsequent process.

  (Claim 6) The second measurement is performed while continuing the state in which the workpiece is bent from the state of the first measurement. The second flow rate is less than the first flow rate. Therefore, the amount of bending of the workpiece by the grinding fluid in the second measurement is smaller than the amount of bending of the workpiece by the grinding fluid in the first measurement. That is, by shifting from the first measurement to the second measurement, the relative position between the workpiece and the grinding wheel changes, and the workpiece is cut by the grinding wheel. By measuring in such a plurality of states, the measurement can be performed in a short time.

  (Claim 7) Since the first measurement is performed in the rough grinding process and the second measurement is performed in the finish grinding process, the grinding accuracy of the workpiece is affected by the grinding fluid in the finish grinding process which is a subsequent process. I can not. That is, the rigidity of the workpiece can be measured with high accuracy as described above while realizing high-precision grinding.

It is a top view of the grinding machine in the embodiment of the present invention. The grinding process by the grinding machine in 1st embodiment of this invention is shown, and the time change of the position of a grindstone stand and the flow volume of a grinding fluid is shown. In the virtual state where the deflection of the workpiece is released when (a) t = Ta, (b) t = T4, (c) t = Tb, (d) t = Tb in FIG. Indicates the relative position. FIG. 2 shows a flowchart of workpiece rigidity calculation processing when the grinding step is executed. The grinding process by the grinding machine in 2nd embodiment of this invention is shown, and the time change of the position of a grindstone head and the flow volume of a grinding fluid is shown. In FIG. 5, (a) a virtual state in which the deflection of the workpiece is released when t = Tc and (b) t = Tc, and (c) the deflection of the workpiece when t = Td and (d) t = Td. In the opened virtual state, the relative position between the grinding wheel and the workpiece is shown. FIG. 5 shows a flowchart of workpiece rigidity calculation processing when the grinding step is executed. When grinding a crankpin, it is a figure which shows the geometric positional relationship of a grinding wheel and a workpiece when t = Ta. When grinding a crankpin, it is a figure which shows the geometric positional relationship of a grinding wheel and a workpiece when t = Tb.

<First embodiment>
(Configuration of grinding machine)
A grinding wheel traverse type grinding machine will be described as an example of the grinding machine of this embodiment. The grinding machine will be described with reference to FIG. As shown in FIG. 1, the grinding machine 1 includes a bed 11 fixed on the floor, and a spindle 12 and a tailstock device 13 that rotatably support the workpiece W fixed to the bed 11 at both ends. Further, the grinding machine 1 includes a grinding wheel base 14 that can move on the bed 11 in the Z-axis direction and the X-axis direction, a grinding wheel 15 that is rotatably supported by the grinding wheel base 14, and a workpiece W provided on the spindle 12. The force sensor 16 that measures the pressing force received from the grinding wheel 15, the sizing device 17 that measures the diameter of the workpiece W, the spindle 12 and the grinding wheel 15 are rotated, and the position of the grinding wheel 15 with respect to the workpiece W is determined. And a control device 18 for controlling. Furthermore, the control device 18 calculates the rigidity of the workpiece W based on the measurement information while grinding.

  Here, although not shown, a nozzle for supplying the grinding fluid toward the grinding point is provided in the vicinity of the grinding wheel 15. Then, the flow rate of the grinding fluid is controlled by the control device 18. Note that the pressing force received by the grinding wheel 15 from the grinding wheel 15 can be measured using the current value of the X-axis driving motor, the force sensor provided on the grinding wheel 15, or the like in addition to the force sensor 16. . Moreover, in this embodiment, the grinding site | part of the workpiece W is a cylindrical outer peripheral surface, Comprising: It is set as the state which the rotation center of the workpiece W and the center of the cylindrical outer peripheral surface of a grinding site | part correspond.

(Description of grinding process)
Next, the grinding process by the grinding machine 1 will be described with reference to FIGS. As shown in FIG. 2, the grinding wheel 15 is moved in the X-axis direction to perform a rough grinding process, and after performing a back-off operation, a finish grinding process is performed. The rough grinding step is a step for increasing the amount of grinding per unit time, and the finish grinding step is a step for reducing the amount of grinding per unit time compared to the rough grinding step. The finish grinding process includes fine grinding and fine grinding. Further, the back-off operation is an operation of moving the grinding wheel 15 away from the workpiece W from a state where the grinding wheel 15 is pressed against the workpiece W. That is, the back-off operation is an operation for releasing the bending amount of the workpiece W from the state where the workpiece W is bent.

  As shown in the upper part of FIG. 2, the grindstone table 14 is pressed against the workpiece W to start the rough grinding process. At this time, the flow rate of the grinding fluid is set to a large flow rate by the control device 18, as shown in the lower part of FIG. Then, when the diameter of the workpiece W measured by the sizing device 17 reaches a set value (set value at the end of rough grinding) (t = T1 in FIG. 2), the movement of the grindstone table 14 is stopped and spark out is performed. Run. At this time, the position of the grindstone platform 14 is X1.

  Here, as shown in FIG. 2, the spark-out is executed at t = T1 to T2. The position of the grinding wheel 15 and the workpiece W at t = Ta during this time will be described with reference to (a) t = Ta in FIG. As shown in (a) t = Ta in FIG. 3, the radius of the workpiece W is r1, and the center of rotation of the workpiece W at this time is O1. Since it is being sparked out, there is no cut into the workpiece W by the grinding wheel 15. However, the workpiece W is bent by the dynamic pressure of the grinding fluid. Therefore, the rotation center O1 of the workpiece W at t = Ta is deviated from the rotation center Oa of the workpiece W in a state in which the deflection amount of the workpiece W is released.

  Subsequently, when t = T2 in FIG. 2 is reached, the back-off operation is started. The time when the back-off operation is completed is T3. That is, at this time, the grinding wheel 15 and the workpiece W are completely separated from each other, and the bending amount of the workpiece W is released. Then, as shown in the lower part of FIG. 2, at this time, the flow rate of the grinding fluid is changed from a large flow rate to a small flow rate. Therefore, the change in the dynamic pressure of the grinding fluid due to the change in the flow rate of the grinding fluid does not affect the workpiece W.

  Subsequently, the finish grinding process is started. First, we start Seken. This is when the grinding wheel 15 contacts the workpiece W at time t = T4, and the position of the grinding wheel base 14 at this time is X3. The position of the grinding wheel 15 and the workpiece W when t = T4 is, as shown in FIG. 3 (b) t = T4, the center of rotation of the workpiece W is Oa. That is, it can be seen that (a) when t = Ta, the amount of deflection of the workpiece W is e1. The amount of deflection e1 is obtained by subtracting X1 from the position X3 of the grinding wheel base 14.

  When the diameter of the workpiece W measured by the sizing device 17 reaches a set value (set value for starting a fine spark start) (t = T5 in FIG. 2), the spark out during the fine study is continued. Execute. At this time, the position of the grindstone base 14 is X2.

  As shown in FIG. 2, the spark-out is executed at t = T5 to T6. At t = Tb during this period, the positions of the grinding wheel 15 and the workpiece W will be described with reference to (c) t = Tb in FIG. As shown in (c) t = Tb in FIG. 3, the radius of the workpiece W is r2 due to the execution of the sharpening, and the rotation center of the workpiece W at this time is O2. In FIG. 3, Δr is a difference between the radii r1 and r2 of the workpiece W when t = Ta and Tb.

  Here, when t = Tb, since the spark-out is in progress, there is no cut into the workpiece W by the grinding wheel 15. However, the workpiece W is bent by the dynamic pressure of the grinding fluid. 3 (d), when t = Tb (virtual), when the diameter of the workpiece W is t = Tb, the bending amount of the workpiece W is released and the grinding wheel 15 contacts the workpiece W. It shows the state.

  As can be seen from FIGS. 3C and 3D, the rotation center O2 of the workpiece W at t = Tb is deviated by e2 from the rotation center Oa of the workpiece W in a state where the deflection amount of the workpiece W is released. ing. The bending amount e2 of the workpiece W is obtained by subtracting X2 from the position X3 of the grindstone table 14.

  The flow rate of the grinding fluid was large when t = Ta, but small when t = Tb. Since the dynamic pressure increases as the flow rate of the grinding fluid increases, the amount of bending of the workpiece W increases. That is, the deflection amount e1 is larger than the deflection amount e2.

  Subsequently, when the time t = T6 is reached, the cutting by the precision research is resumed. Then, when the diameter of the workpiece W measured by the sizing device 17 reaches a set value (set value for finishing the fine grinding) (t = T7 in FIG. 2), fine grinding is started. Thereafter, when the diameter of the workpiece W measured by the sizing device 17 reaches a set value (set value for end of fine grinding) (t = T8 in FIG. 2), a spark-out is executed and the finish grinding process is finished. To do.

(Workpiece rigidity calculation process)
Next, the rigidity calculation process of the workpiece W will be described with reference to FIG. This process is a process performed by the control device 18. However, in the following, only the processing related to the calculation of the rigidity of the workpiece W is extracted from the processing by the control device 18.

  First, the position X1 of the grinding wheel base 14, the radius r1 of the workpiece W, and the pressing force F1 that the workpiece W receives from the grinding wheel 15 are measured during t = Ta with a large flow rate of the grinding fluid (S1 in FIG. 4). (Corresponding to “measuring means” and “measuring step” of the present invention). As shown in FIG. 2, the period between t = Ta is when the spark-out is being executed. Accordingly, the workpiece W is bent only by the dynamic pressure of the grinding fluid having a large flow rate. Subsequently, the grinding fluid is changed from a large flow rate to a small flow rate (S2 in FIG. 4). This process is performed when t = T3 in FIG. That is, after the back-off operation is performed, the flow rate of the grinding fluid is changed.

  Subsequently, during t = Tb with the grinding fluid at a small flow rate, the position X2 of the grinding wheel base 14, the radius r2 of the workpiece W, and the pressing force F2 received by the workpiece W from the grinding wheel 15 are measured (FIG. 4). S3) (corresponding to “measuring means” and “measuring step” of the present invention). As shown in FIG. 2, the spark-out is also executed during t = Tb. Accordingly, the workpiece W is bent only by the dynamic pressure of the grinding fluid having a small flow rate.

  Subsequently, the rigidity K of the workpiece W is calculated using each information measured in two different states of S1 and S3 in FIG. 4 (S4 in FIG. 4). The rigidity K is calculated according to the equation (1). That is, the rigidity K of the workpiece W can be obtained by dividing the difference in the pressing force (dynamic pressure) by the grinding fluid by the difference in the amount of deflection of the workpiece W according to Hooke's law. Thus, the rigidity of the workpiece W can be calculated without using a dedicated device.

  And the control apparatus 18 estimates the bending amount of the workpiece W using the calculated rigidity K of the workpiece W, and correct | amends the command position of the grindstone base 14 according to the estimated bending amount of the workpiece W. By doing in this way, while being able to improve grinding precision, grinding time can be shortened by reducing the uncut residue by a rough grinding process.

  Furthermore, each information is measured in the spark-out state. Therefore, each information in a stable state can be measured. Therefore, also from this, the rigidity K of the workpiece W can be calculated with high accuracy.

  Further, in the present embodiment, when the back-off operation is performed to release the bending amount of the workpiece W, the flow rate of the grinding fluid is changed. That is, it is not during grinding that the amount of deflection of the workpiece W changes as the flow rate of the grinding fluid changes. Therefore, the flow rate change of the grinding fluid does not affect the machining accuracy of the workpiece W.

  Moreover, the grinding fluid in the rough grinding process was set to a large flow rate, and the grinding fluid in the finish grinding step was set to a small flow rate. Generally, the more the post-process, the higher the grinding accuracy of the workpiece W. Further, the greater the flow rate of the grinding fluid, the greater the effect on the grinding accuracy of the workpiece W. That is, by making the flow rate in the finish grinding step smaller than the flow rate in the rough grinding step, the grinding accuracy of the workpiece W in the finish grinding step can be prevented from being affected by the grinding fluid.

(Method for deriving workpiece rigidity)
The rigidity K of the workpiece W is calculated according to the above-described equation (1). Below, the derivation | leading-out method of Formula (1) is demonstrated. The basic idea is to use Hooke's law F = K · x. However, it is not easy to obtain the position of the grinding wheel base 14 in a state in which the grinding wheel 15 and the workpiece W are in contact with each other with zero deflection with high accuracy. Therefore, in two different states, the workpiece W is bent. Each piece of information measured in the state where the workpiece W is bent is a highly accurate value. Then, by obtaining the force difference ΔF and the displacement difference Δx in two different states, the highly accurate rigidity K is derived.

  First, when t = Ta where the grinding fluid is a large flow rate, the relationship of equation (2) can be obtained from FIGS. 3 (a) and 3 (b). Further, when t = Tb with a small flow rate of the grinding fluid, the relationship of Expression (3) can be obtained from (c) and (d) of FIG.

  Next, when both sides of Expressions (2) and (3) are subtracted, Expression (4) is obtained. When formula (4) is arranged, formula (5) is obtained. Then, e1 and e2 on the left side of the equation (5) are obtained by substituting the Hooke's law F1 = K · e1 and F2 = K · e2 into the equation (6). When formula (6) is arranged for K, formula (1) described above can be obtained.

<Deformation mode>
In the above-described embodiment, measurement of each information when the grinding fluid is set to a small flow rate was performed in the middle of precise research. In addition to this, it can be performed between Seken and Microken, in the middle of Microken, or at the spark-out after Microken.

<Second embodiment>
Next, a second embodiment will be described with reference to FIGS. In the above embodiment, when the back-off operation is performed to release the bending amount of the workpiece W, the flow rate of the grinding fluid is changed. In the present embodiment, the flow rate of the grinding fluid is changed while continuing the state where the workpiece W is bent without performing the back-off operation.

(Description of grinding process)
The grinding process of this embodiment is demonstrated with reference to FIG. 5 and FIG. As shown in the upper part of FIG. 5, a rough grinding process is performed, and when the diameter of the workpiece W measured by the sizing device 17 reaches a set value (set value at the end of rough grinding) (t = T11 in FIG. 5). , Perform a spark out. At this time, the position of the grindstone platform 14 is X1. At this time, the flow rate of the grinding fluid is set to a large flow rate by the control device 18, as shown in the lower part of FIG.

  Then, at t = Tc during the spark-out, the positions of the grinding wheel 15 and the workpiece W are as shown in FIG. 6 (a) t = Tc. 6B, at t = Tc (virtual), when the diameter of the workpiece W is t = Tc, the bending amount of the workpiece W is released, and the grinding wheel 15 contacts the workpiece W. It shows the state. As can be seen from FIGS. 6A and 6B, the rotation center O1 of the workpiece W at t = Tc is deviated by e1 from the rotation center Oa of the workpiece W in a state where the deflection amount of the workpiece W is released. ing.

  Subsequently, when t = T12, as shown in the lower part of FIG. 5, the flow rate of the grinding fluid is changed from a large flow rate to a small flow rate, and the finish grinding process is started. However, the spark-out state continues. If it does so, since the dynamic pressure (pressing force) of a grinding fluid becomes small, the bending amount of the workpiece W will reduce. Therefore, the workpiece W is ground by the grinding wheel 15, and the diameter of the workpiece W is reduced.

  At t = Td during the spark-out, the positions of the grinding wheel 15 and the workpiece W are as shown in FIG. 6 (c) t = Td. 6 (d) t = Td (virtual), when the diameter of the workpiece W is t = Td, the bending amount of the workpiece W is released and the grinding wheel 15 contacts the workpiece W. It shows the state. As can be seen from FIGS. 6C and 6D, the rotation center O2 of the workpiece W at t = Td is deviated by e2 from the rotation center Oa of the workpiece W in a state in which the deflection amount of the workpiece W is released. ing.

  Subsequently, when t = T13, fine grinding is started, and when the diameter of the workpiece W measured by the sizing device 17 reaches a set value (set value for completion of fine grinding) (t = T14 in FIG. 6). Start the fine research. Thereafter, when the diameter of the workpiece W measured by the sizing device 17 reaches a set value (set value for ending the fine grinding) (t = T15 in FIG. 6), the spark-out is executed and the finish grinding process is finished. To do.

(Workpiece rigidity calculation process)
Next, the rigidity calculation processing of the workpiece W will be described with reference to FIG. The procedure of the calculation process is the same as that in the above embodiment. That is, r1 and F1 are measured during t = Tc with a large flow rate of the grinding fluid (S11 in FIG. 7). In this embodiment, since the position of the grindstone base 14 is the same in two different states, the position of the grindstone base 14 is not measured.

  Subsequently, the grinding fluid is changed from a large flow rate to a small flow rate (S12 in FIG. 7), and r2 and F2 are measured during t = Td when the grinding fluid is a small flow rate (S13 in FIG. 7). Also at this time, the position of the grinding wheel base 14 is not measured.

  Subsequently, the rigidity K of the workpiece W is calculated using each information measured in two different states of S11 and S13 in FIG. 7 (S14 in FIG. 7). Specifically, it is calculated according to equation (7).

  The derivation method is based on the same concept as the above embodiment except for the following points. In the present embodiment, the above formula (3) is substituted as in formula (8). This is because X2 in the above embodiment becomes X1 in the present embodiment because the position of the grindstone table 14 is the same in the measurement at a high flow rate and the measurement at a low flow rate of the grinding fluid.

  Also in the present embodiment, the rigidity K of the workpiece W can be calculated with high accuracy as described above. Moreover, the measurement at the time of the small flow rate is performed while continuing the state in which the workpiece W is bent from the state of the measurement at the time of the large flow rate. Therefore, the bending amount e2 of the workpiece W due to the grinding fluid in the measurement at the small flow rate is smaller than the bending amount e1 of the workpiece W due to the grinding fluid in the measurement at the large flow rate. That is, the relative position between the workpiece W and the grinding wheel 15 is changed by shifting from the high flow rate state to the small flow rate state, and the workpiece W is cut by the grinding wheel 15. Thus, the measurement can be performed in a short time by measuring in a plurality of states without performing the back-off operation.

<Third embodiment>
The grinding process of the third embodiment will be described with reference to FIG. In the first embodiment, the grinding portion of the workpiece W is a cylindrical outer peripheral surface. However, in this embodiment, for example, a crank pin of a crankshaft or a cam portion of a camshaft is a grinding portion. That is, in this embodiment, the grinding part of the workpiece W is formed in an eccentric or non-circular shape. In the following, the crank pin Wa is taken as an example.

  In the present embodiment, the same grinding process as that in the first embodiment is executed. That is, the calculation process of the rigidity of the workpiece W is substantially the same as the process shown in FIG. However, the amount of bending of the crank pin Wa that is a grinding part differs depending on the phase of the crank shaft that is the workpiece W. Therefore, in this embodiment, the rigidity K (θ) of the workpiece W corresponding to the phase θ of the workpiece W is calculated.

  That is, the pressing force received from the grinding wheel 15 by the position X1 of the grinding wheel base 14, the radius r1 (θ) of the crank pin Wa and the crank pin Wa during t = Ta (shown in FIG. 2) when the grinding fluid is at a large flow rate. The force F1 (θ) is measured (S1 in FIG. 4). The geometric positional relationship between the crankpin Wa and the grinding wheel 15 at this time is as shown in FIG.

  In FIG. 8, the solid line indicates the current position of the grinding wheel 15 and the crank pin Wa. A broken line indicates the grinding wheel 15 and the crank pin Wa in a state where the bending amount of the crank pin Wa is zero and the grinding wheel 15 and the crank pin Wa are in contact with each other. The short two-dot chain line indicates the current center of rotation of the workpiece W and the locus of the center of the crankpin Wa. The long two-dot chain line indicates the locus of the rotation center of the workpiece W and the center of the crank pin Wa when the amount of bending of the crank pin Wa is zero.

  st is the eccentric amount of the crank pin Wa, r1 (θ), r2 (θ) are the radii of the crank pin Wa, R is the radius of the grinding wheel 15, θ is the phase of the workpiece W, and β is the grinding wheel The angle formed by the line segment connecting the center of 15 and the grinding point and the X-axis direction.

  That is, the relationship corresponding to Expression (2) in the first embodiment is expressed as Expression (9). Since γ is smaller than β, cos (β + γ) can be approximated to cos β.

  Further, during t = Tb (shown in FIG. 2) when the grinding fluid is at a small flow rate, the position X2 of the grinding wheel base 14, the radius r2 (θ) of the crank pin Wa and the pressing received from the grinding wheel 15 by the crank pin Wa. The force F2 (θ) is measured (S3 in FIG. 4). The geometrical positional relationship between the crankpin Wa and the grinding wheel 15 at this time is as shown in FIG. That is, the relationship corresponding to Expression (3) in the first embodiment is expressed as Expression (10).

  And the rigidity K ((theta)) of the workpiece W according to phase (theta) is calculated using each measured information (S4 of FIG. 4). Specifically, it is calculated according to equation (11).

  Here, in formula (11), β can be obtained as follows using each piece of measured information. From the geometrical relationship of FIG. 8, the equation (12) can be obtained from the relationship of the Y coordinate (vertical direction coordinate of FIG. 8) of the center of the crankpin Wa when t = Ta. When Expression (12) is expressed with respect to sin β, Expression (13) is obtained. Here, ΔY is very small as compared with (R + r1 (θ)), and therefore can be approximated as the following equation (13). Then, when Expression (13) is expressed with respect to β, Expression (14) is obtained. By substituting this equation (14) into the above equation (11), the stiffness K (θ) can be obtained using each information.

<Fourth embodiment>
The fourth embodiment is a case where the grinding process of the second embodiment is applied and the crank pin Wa is used as a grinding part as in the third embodiment. In this case, the stiffness K (θ) corresponding to the phase θ is expressed as in Expression (15).

DESCRIPTION OF SYMBOLS 1: Grinding machine, 15: Grinding wheel, 18: Control apparatus (measuring means, rigidity calculation means), F1, F2: Pushing force, K: Workpiece rigidity, r1, r2: Workpiece radius, W: Workpiece Wa: Crank pin, X1, X2: Position of grinding wheel, θ: Phase

Claims (8)

In each of a plurality of states in which the amount of bending of the workpiece is changed by changing the flow rate of the grinding fluid supplied to the grinding point of the workpiece, the position of the grinding wheel, the diameter of the workpiece, and the work by the grinding wheel Measuring means for measuring the pressing force against the object,
Rigidity calculating means for calculating the rigidity of the workpiece based on each of the measured position, diameter, and pressing force;
A grinding machine comprising   In each of a plurality of states in which the measuring means is in a spark-out state and the amount of bending of the workpiece is changed by changing the flow rate of the grinding fluid supplied to the grinding point of the workpiece, The grinding machine of Claim 1 which measures a diameter and pressing force. The workpiece has an eccentric or non-circular shape;
The measuring means measures the position, diameter and pressing force according to the phase of the workpiece;
The grinding machine according to claim 1 or 2, wherein the rigidity calculating means calculates rigidity according to a phase of the workpiece. The first measurement is a measurement of the position, diameter and pressing force in a state where the workpiece is bent with the flow rate of the grinding fluid supplied to the grinding point of the workpiece as the first flow rate,
The second measurement is a flow rate of the grinding fluid supplied to the grinding point of the workpiece after performing the back-off operation and releasing the bending amount of the workpiece after the first measurement. Measurement of the position, diameter and pressing force in a state where the workpiece is bent again as a different second flow rate,
The measurement means performs each of the first measurement and the second measurement,
The rigidity calculating means calculates the rigidity of the workpiece based on the position, diameter and pressing force measured in each of the first measurement and the second measurement;
The grinding machine according to any one of claims 1 to 3.   The grinding machine according to claim 4, wherein the second flow rate is less than the first flow rate. The first measurement is a measurement of the position, diameter and pressing force in a state where the workpiece is bent with the flow rate of the grinding fluid supplied to the grinding point of the workpiece as the first flow rate,
In the second measurement, the flow rate of the grinding fluid supplied to the grinding point of the workpiece is set to a second flow rate smaller than the first flow rate while continuing the state where the workpiece is bent from the state of the first measurement. Measurement of the position, diameter and pressing force in a state,
The measurement means performs each of the first measurement and the second measurement,
The rigidity calculating means calculates the rigidity of the workpiece based on the position, diameter and pressing force measured in each of the first measurement and the second measurement;
The grinding machine according to any one of claims 1 to 3. The first measurement is performed in a rough grinding process,
The grinding machine according to claim 5 or 6, wherein the second measurement is performed in a finish grinding step. In each of a plurality of states in which the amount of bending of the workpiece is changed by changing the flow rate of the grinding fluid supplied to the grinding point of the workpiece, the position of the grinding wheel, the diameter of the workpiece, and the work by the grinding wheel A measuring process for measuring the pressing force against the object,
A rigidity calculating step for calculating the rigidity of the workpiece based on each of the measured position, diameter, and pressing force;
A method for calculating the rigidity of a workpiece in a grinding machine comprising:

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