JP7135288B2 - Grinding machine and grinding method - Google Patents

Description

The present invention relates to a grinding machine and grinding method.

Patent Literature 1 describes a grinding machine capable of grinding a cylindrical workpiece having an eccentric cylindrical portion, for example, a crankshaft of an air conditioner compressor. This grinder performs grinding while one end of a crankshaft of an air conditioner compressor is supported by a main shaft in a cantilever manner.

However, when this grinder grinds a long workpiece, such as a crankshaft of an automobile engine (hereinafter simply referred to as a "crankshaft"), the crankshaft is greatly flexed due to grinding resistance and the like. It is difficult to maintain high grinding accuracy of the crankshaft.

Patent Document 2 describes a grinder that grinds a crank journal and a crank pin (eccentric pin) of a crank shaft. This grinding machine performs grinding while both ends of the crankshaft are supported and one end is gripped by a center and a center having a chuck. With this grinder, it is possible to maintain high grinding accuracy of the crankshaft.

A method of manufacturing a crankshaft is to manufacture a crankshaft material by forging, and harden a crankshaft material crankshaft journal and crankpin by high frequency. This induction hardening causes the crankshaft to bend, so the crankshaft is straightened by a straightener. Then, a grinding machine is used to grind the crankshaft into the final shape.

Japanese Patent No. 3840389 Japanese Patent No. 5473006

In a grinder, for example, when the surface layer of a crankpin of an in-line 4-cylinder single-plane crankshaft is removed by grinding in order from the crankpin on one end side, the internal stress generated by the straightening machine is removed in order from the crankpin on the one end side. When released, the above bend is restored and the crankshaft is deformed. For this reason, variations occur in the piston strokes of crankpins other than the crankpin on the other end side with respect to the crank journal (hereinafter simply referred to as "crankpin eccentricity").

In order to reduce this variation, the rough grinding process is first performed from the crankpin on the one end side, and then the finish grinding process is performed sequentially from the crankpin on the one end side. At this time, the minimum machining allowance that can remove the amount of deformation generated in the rough grinding process is set as the finish machining allowance in the finish grinding process.

In a conventional grinder, the variation in the eccentricity of the crankpin can be reduced by the above-described grinding process, and a grinder capable of further reducing the variation is desired. In addition, in the conventional grinder, the finish grinding process must be completed after the rough grinding process for all the crankpins is completed, so there is a limit to the improvement of the grinding efficiency.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a grinding machine and a grinding method capable of improving grinding accuracy and grinding efficiency.

(Grinder)
The grinding machine of the present invention comprises: a grinding wheel table which rotatably supports a grinding wheel and has a grinding wheel drive motor which rotates the grinding wheel; A headstock having a workpiece driving motor, a feeding device for relatively moving the grinding wheel toward and away from the work piece in a direction intersecting the rotation axis of the work piece, and controlling the feeding operation of the feeding device. and a control device for grinding the workpiece with the grinding wheel.

The control device controls a correction amount at a processed portion of the workpiece when the workpiece is bent in a direction intersecting the rotation axis of the workpiece before grinding, and the workpiece after grinding. an input device for inputting an eccentricity error with respect to the rotation axis of the workpiece at a machining portion of the object; and a storage device for storing a correlation between the input correction amount and the eccentricity error , wherein the correlation is , to obtain the eccentricity error of the machining portion of the workpiece to be currently ground corresponding to the input correction amount of the machining portion of the workpiece to be currently ground, and calculate the eccentricity error and By controlling the feeding operation of the feeding device in consideration of the eccentric phase from the rotation axis of the workpiece at the machining portion of the workpiece to be currently ground, the workpiece to be currently ground by the grinding wheel Grinding process.

(Grinding method)
The grinding method for grinding a workpiece with the above-described grinding machine of the present invention is characterized in that the workpiece is bent in a direction intersecting with the rotation axis of the workpiece before grinding, and the workpiece is corrected for bending. and an input step of inputting the correction amount at the machined part and the eccentricity error with respect to the rotation axis of the workpiece at the machined part of the workpiece after grinding, and the correlation between the input correction amount and the eccentricity error a storage step of storing the relationship; and referring to the correlation, storing the machining portion of the workpiece to be currently ground corresponding to the input correction amount of the machining portion of the workpiece to be currently ground. By obtaining an eccentricity error and controlling the feed operation of the feed device in consideration of the eccentricity error and the eccentricity phase of the machining portion of the workpiece to be currently ground from the rotation axis of the workpiece , and a grinding step of grinding the workpiece to be currently ground with a grinding wheel.

According to the grinder and the grinding method of the present invention, the feeding operation of the grinding wheel is determined from the correction amount at the processed portion of the workpiece before grinding that is bent in the direction that intersects the rotation axis of the workpiece. Since the control is performed based on the eccentricity error with respect to the rotation axis of the workpiece at the machining portion of the workpiece, it is possible to accurately grind each workpiece and improve the grinding accuracy. Further, even if there are a plurality of grinding positions on the workpiece, each of the grinding positions can be subjected to, for example, rough grinding and finish grinding, so that the grinding efficiency can be improved.

It is a top view of the grinding machine in the embodiment of the present invention. It is the figure which looked at the crankshaft of grinding processing object from the radial direction. 4 is a flow chart for explaining a method of manufacturing a crankshaft; 4 is a flowchart for explaining a method of grinding a crankshaft; It is the figure which looked at the bending state of the crankshaft from the radial direction. It is the figure which looked at the state which corrects the bending of the crankshaft from the radial direction. FIG. 4 is a view of the crankshaft viewed from the radial direction for explaining the correction amount of the crankshaft; FIG. 5 is a diagram showing the positional relationship among the rotation center of the crank journal, the center of the crankpin, and the rotation center of the grinding wheel when the phase of the crank journal is 0°; FIG. 5 is a diagram showing the positional relationship among the rotation center of the crank journal, the center of the crank pin, and the rotation center of the grinding wheel when the phase of the crank journal is 90°; FIG. 5 is a diagram showing the positional relationship among the rotation center of the crank journal, the center of the crankpin, and the rotation center of the grinding wheel when the phase of the crank journal is 180°; FIG. 5 is a diagram showing the positional relationship among the rotation center of the crank journal, the center of the crankpin, and the rotation center of the grinding wheel when the phase of the crank journal is 270°; 4 is a graph showing the relationship between the amount of correction of the crankshaft before grinding and the amount of deformation of the crankshaft after grinding (error in eccentricity of the crankpin). FIG. 5 is a diagram showing the positional relationship among the rotation center of a crank journal, the center of a crankpin, and the rotation center of the grinding wheel, for explaining the method of calculating the feed position of the grinding wheel during grinding. FIG. 5 is a diagram showing the positional relationship between the rotation center of the crank journal, the center of the crankpin, and the rotation center of the grinding wheel, for explaining another example of calculating the feeding position of the grinding wheel during grinding.

(1. Configuration of Grinding Machine)
As an example of the grinding machine of the present embodiment, a twin-head grinding machine will be described with reference to the drawings. In the following description, as shown in FIG. 2, the workpiece to be ground by the grinder 1 is an in-line four-cylinder single-plane crankshaft W, and the grinding portion is the crank pin P1- Let it be P4.

The crankpins P1-P4 are formed in a cylindrical shape having central axes Lp radially eccentric from the central axes Lj of the cylindrical crank journals J1-J5.
As shown in FIG. 1, the grinder 1 has a bed 11 fixed on the floor, and a headstock 12 and a tailstock 13 are attached to the bed 11 for rotatably supporting a crankshaft W at both ends.

A master spindle Cm (C-axis) is rotatably supported on the headstock 12, and a center 14 supporting one end of the crankshaft W and a three-jaw chuck 15 are attached to the tip of the master spindle Cm. The master spindle Cm is advanced and retracted in an axial direction parallel to the Z-axis by an advance/retreat drive device 16, and is rotationally driven around an axis parallel to the Z-axis by a master servomotor 17 (workpiece drive motor) having an encoder 17a. .

A slave spindle Cs (C-axis) is rotatably supported on the tailstock 13 coaxially with the master spindle Cm, and a center 18 supporting the other end of the crankshaft W is attached to the tip of the slave spindle Cs. The slave spindle Cs is advanced and retracted in an axial direction parallel to the Z-axis by a center pressurizing device 19, and rotated about an axis parallel to the Z-axis in synchronization with the master spindle Cm by a slave servomotor 20 having an encoder 20a. be done.

The forward/backward drive device 16 includes a master moving motor 16a, a feed screw 16b, a guide 16c, a slider 16d, and a floating joint 16e. A feed screw 16b is connected to the motor shaft of the master moving motor 16a. The guide 16c is arranged parallel to and parallel to the feed screw 16b.

A feed screw 16b is screwed into the slider 16d, and a guide 16c is passed through the slider 16d. Further, the master spindle Cm is connected to the slider 16d via a floating joint 16e. The master spindle Cm is advanced or retracted by a predetermined amount in the axial direction parallel to the Z-axis by moving the slider 16d along the guide 16c by rotating the feed screw 16b driven by the master moving motor 16a.

The center pressing device 19 comprises a slave moving motor 19a, a feed screw 19b, a guide 19c, a slider 19d and a spring 19e. A feed screw 19b is connected to the motor shaft of the slave movement motor 19a. The guide 19c is arranged parallel to and parallel to the feed screw 19b.

A feed screw 19b is screwed into the slider 19d, and a guide 19c is passed therethrough. Further, the slider 19d presses the slave spindle Cs toward the workpiece W via a spring 19e, and movably connects the slave spindle Cs to the side opposite to the workpiece W via a stopper rod (not shown).

The slave main shaft Cs is advanced and retreated by a predetermined amount in the axial direction parallel to the Z-axis by moving the slider 19d along the guide 19c by rotating the feed screw 19b driven by the slave movement motor 19a. Both ends of the crankshaft W are gripped by chucks 15, and are moved at centers 14 and 18 by moving the master main shaft Cm and the slave main shaft Cs in the axial direction parallel to the Z-axis by the advance/retreat drive device 16 and the center pressure device 19. Sandwiched and supported.

Since the master spindle Cm is fixed to the slider 16d by the floating joint 16e so as not to move in the axial direction parallel to the Z-axis, the slave spindle Cs is moved by the center pressure device 19 so as to compress the spring 19e. By moving in the axial direction parallel to the axis, it is possible to apply pressure to the crankshaft W according to the amount of compression of the spring 19e.

Further, on the bed 11, two tables 23 movable in the Z-axis direction by a Z-axis servomotor 21 having an encoder 21a and a feed screw 22 are arranged side by side in an axial direction parallel to the Z-axis.

In each table 23, an X-axis servomotor 24 (feeding device) having an encoder 24a and a feed screw 25 (feeding device) rotate in an axial direction parallel to the X-axis (a direction intersecting the rotation axis of the crankshaft W). Two wheelheads 26 that are movable (approachable to and away from the crankshaft W) are arranged side by side in an axial direction parallel to the Z-axis.

A grinding wheel 28 is rotatably supported on each grinding wheel 26 by a grinding wheel drive motor 27 about an axis parallel to the Z axis, and a coolant nozzle 29 (FIG. 6A) for supplying coolant toward the grinding point. ) is provided. Further, the bed 11 is provided with a sizing device 30 for measuring the diameter of the crankshaft W (crankpins P1-P4, crank journals J1-J5).

Further, the grinding machine 1 is provided with a control device 31 for rotating the master spindle Cm, the slave spindle Cs and the grinding wheel 28 and for controlling the feeding operation of the grinding wheel 28 relative to the crankshaft W.

Although the details will be described later, the control device 31 is provided with an input device 32 for inputting the correction amount when the deformation of the crankshaft W before grinding is corrected and the deformation amount of the crankshaft W after grinding. and a storage device 33 for storing a table (correlation) representing the relationship between the amount of correction and the amount of deformation.

The control device 31 refers to the table to obtain the amount of deformation of the crankshaft W to be currently ground that corresponds to the input correction amount of the crankshaft W to be currently ground. By controlling the feeding operation of the wheel 28, the grinding wheel 28 grinds the crankshaft W (crank pins P1-P4, crank journals J1-J5).

(2. Crankshaft manufacturing method)
Next, a method for manufacturing the crankshaft W will be described. As described in the background art, when the surface layers of the crankpins P1 to P4 are removed by grinding in order of the crankpins P1 to P4 in the grinder, the internal stress generated by the straightener is released in order, and induction hardening is performed. The bending of the crankshaft W returns and the crankshaft W is deformed.

For this reason, the eccentricity and the like of the crankpins P1 to P3 other than the crankpin P4 to be ground lastly vary. The inventor of the present invention found that the amount of deformation of the crankshaft W in the grinder, that is, the error in the amount of eccentricity of the crankpins P1-P4 has a correlation with the amount of straightening of the crankshaft W in the straightening machine. A method of deriving the correlation between the amount of correction of the crankshaft W and the error in the amount of eccentricity of the crankpins P1-P4 will be described below with reference to the drawings.

The method of deriving the correlation between the amount of correction of the crankshaft W and the error in the amount of eccentricity of the crankpins P1-P4 is as follows. The crank journals L1-L5 and the crank pins P1-P4 made of W material are quenched (step S2 in FIG. 3). Since this induction hardening causes the crankshaft W to bend, the amount of bending at this time is measured as the first amount of bending B1 (step S3 in FIG. 3).

Specifically, as shown in FIG. 5A, the crankshaft W bends in a direction intersecting with the rotation axis Lw. In FIG. 5A, illustration of the crankpins P1 to P4 is omitted, and this is an example in which the amount of bending of the crank journal J3 is maximized. Therefore, the distance between the rotation axis Lw of the crankshaft W and the central axis Lj3 of the crank journal J3 is measured as the first bending amount B1.

Next, the bending of the crankshaft W is corrected by a straightener (step S4 in FIG. 3). Although the bending of the crankshaft W is corrected by the straightener, the crankshaft W remains slightly bent, so the amount of bending at this time is measured as the second amount of bending B2 (step S5 in FIG. 3).

Specifically, as shown in FIG. 5B, a load H is applied to the crank journal J3 in a direction perpendicular to the rotation axis Lw of the crankshaft W to correct the bending of the crankshaft W (from the state indicated by the dashed line in the drawing to the solid line). Then, as shown in FIG. 5C, the distance between the rotation axis Lw of the crankshaft W and the central axis Lj3 of the crank journal J3 is measured as the second bending amount B2.

Then, the difference between the first bending amount B1 and the second bending amount B2 is calculated as the correction amount B3 of the crankshaft W by the straightener (step S6 in FIG. 3). The calculated correction amount B3 of the crankshaft W is input by the operator from the input device 32 of the control device 31 of the grinder 1 (input step) and stored in the storage device 33 . Then, the crankshaft W is ground by the grinding machine 1 to obtain the final shape of the crankshaft W (step S7 in FIG. 3).

Here, the positions of the crankpin P1 and the grinding wheel 28 in grinding the crankshaft W will be described with reference to FIGS. 6A to 6D. However, in FIGS. 6A to 6D, the crankshaft W is shown as not deformed. Further, hereinafter, the left direction in the drawing is referred to as the forward feed direction of the grinding wheel 28 and the right direction in the drawing is referred to as the backward feed direction of the grinding wheel 28 .

Further, the rotational phase α of the crank journal J3 (hereinafter referred to as the phase α of the crank journal J3) is defined as the rotational phase α of the crank journal J3 relative to the straight line connecting the rotational center Oj3 of the crank journal J3 and the rotational center Og of the grinding wheel 28. The angle formed by a straight line connecting the center Oj3 and the center Op1 of the crankpin P1 . Note that the crank journal J3 is omitted from FIGS. 6A to 6D.

As shown in FIG. 6A, when the phase α of the crank journal J3 is 0°, the center Op1 of the crank pin P1 is positioned on a straight line connecting the rotation center Oj3 of the crank journal J3 and the rotation center Og of the grinding wheel 28. , and the center of rotation Og of the grinding wheel 28 is at the most retracted position in the backward feeding direction.

That is, the grinding point Q between the crankpin P1 and the grinding wheel 28 is located on a straight line connecting the center Op1 of the crankpin P1, the rotation center Oj3 of the crank journal J3, and the rotation center Og of the grinding wheel 28 . Coolant supplied from the coolant nozzle 29 is supplied toward the grinding point Q from the upper side of the grinding wheel 28 .

As shown in FIG. 6B, when the phase α of the crank journal J3 is 90°, the center Op1 of the crank pin P1 is eccentric to the uppermost position with respect to the rotation center Oj3 of the crank journal J3. The center of rotation Og of is advanced in the forward feeding direction from the position when the phase α of the crank journal J3 is 0°.

As shown in FIG. 6C, when the phase α of the crank journal J3 is 180°, the center Op1 of the crank pin P1 is on the extension of the straight line connecting the rotation center Oj3 of the crank journal J3 and the rotation center Og of the grinding wheel 28. The rotation center Og of the grinding wheel 28 is at the most advanced position in the feed direction from the position when the phase α of the crank journal J3 is 90°.

As shown in FIG. 6D, when the phase α of the crank journal J3 is 270°, the center Op1 of the crank pin P1 is at the lowest eccentric position with respect to the rotation center Oj3 of the crank journal J3. The center of rotation Og of is retreated in the backward feed direction from the position when the phase α of the crank journal J3 is 180°.

In grinding the crankpin P1, the operations of FIGS. 6A to 6D are repeated. The same applies to the other crankpins P2-P4. After the grinding process is completed, the internal stress generated by the straightening machine is released in order, and the crankshaft W is deformed by returning the bending caused by the induction hardening. It is regarded as an error (step S8 in FIG. 3).

Specifically, since the center Op1 of the crankpin P1 is deformed in the radial direction with respect to the rotation axis Lw of the crankshaft W, the center Op1 of the crankpin P1 after the grinding process and the rotation axis Lw of the crankshaft W are not aligned. Measure distance.

Then, the difference between the measured distance and the designed distance between the center Op1 of the crankpin P1 and the rotational axis Lw of the crankshaft W is obtained, and this difference is defined as the eccentricity error ΔS of the crankpin P1. The calculated eccentricity error ΔS of the crankpin P1 is input by the operator from the input device 32 of the control device 31 of the grinder 1 (input step) and stored in the storage device 33 .

As described above, the relationship between the correction amount B3 of the crankshaft W obtained in step S6 and the eccentricity error ΔS of the crankpin P1 obtained in step S8 is stored in the storage device 33 as a table (step S9 in FIG. 3, storage step) to end all the processes. By performing the above processing while varying the correction amount B3 of the crankshaft W, the above table is stored in the storage device 33 as a database.

For example, as shown in FIG. 7, there is a linear correlation between the correction amount B3 of the crankshaft W and the eccentricity error ΔS of the crankpins P1-P4. In FIG. 7, the error ΔS of the eccentricity of each of the crankpins P1 to P4 is plotted when there are four correction amounts B3 of the crankshaft W, and each plot is linearly approximated.

Also, the error ΔS of the eccentricity of the crankpins P1-P4 is the value obtained after first grinding the two crankpins P1 and P2 at the same time and then grinding the remaining two crankpins P3 and P4 at the same time. . Thus, by obtaining the correction amount B3 of the crankshaft W to be ground, the eccentricity error ΔS of each of the crankpins P1 to P4 can be obtained.

(3. Overview of Grinding Method)
Next, the outline of the grinding method in this embodiment will be described with reference to the drawings. Here, in this example, as shown in FIG. 8, the case where the crankpin P1 is ground by the grinding wheel 28 will be described. Note that the radius of the grinding wheel 28 is R, and the radius of the crank pin P1 after grinding indicated by the solid line in the drawing is r. Also, the other crankpins P2-P4 can be similarly ground.

In this grinding control, it is necessary to vary the feed position of the grinding wheel 28, that is, the distance X between the rotation axis Lw of the crankshaft W and the rotation center Og of the grinding wheel 28 according to the phase α of the crank journal J3. In FIG. 8, a straight line M1 connecting the rotation axis Lw of the crankshaft W and the rotation center Og of the grinding wheel 28 is compared with a straight line M2 connecting the rotation center Og of the grinding wheel 28 and the center Op1 of the crank pin P1 after grinding. Let β be the angle formed by

The center Opa1 of the crankpin Pa1 before grinding indicated by the one-dot chain line in FIG. It is assumed that the crankpin P1 after grinding is deviated by an error ΔS of the eccentricity amount in the direction of a straight line M3 connecting . The eccentricity of the crankpin P1 after grinding is S-ΔS.

When set as described above, the grinder 1 has the same center as the center Op of the crankpin P1 after grinding, and includes the crankpin Pa1 before grinding. Grinding of the pin Pb1 is controlled. In this case, as the grinding progresses, the radius of the virtual crankpin Pb1 changes, but the eccentricity of the virtual crankpin Pb1 is constant at S-ΔS.

In this example, the radius of the virtual crankpin Pb1 is set to r+Δr1+Δr2+ΔS at the beginning of the rough grinding process, and the radius of the virtual crankpin Pb1 is set to is set to r + Δr1 + Δr2, and in the finish grinding (after the end of the grinding for Δr1), the radius of the virtual crankpin Pb1 is set to r + Δr2, and after the end of the finish grinding (after the end of the grinding for Δr2) 2, the case where the radius of the virtual crankpin Pb1 is set to r will be described. Δr1 is the depth of cut during rough grinding, and Δr2 is the depth of cut during finish grinding.

The initial stage of rough grinding (before grinding for ΔS) in the grinder 1 is performed under the conditions of the following equation (1). In equation (1), since R, S, ΔS, Δr1, Δr2, and α are known values, β can be obtained. Therefore, X can be calculated by the following formula (2). Then, a table showing the relationship between α and X is created, and the feeding operation of the grinding wheel 28 is controlled according to this table.

The latter stage of the rough grinding process in the grinder 1 (after finishing the grinding process for ΔS) is performed under the conditions of the following formula (3). In equation (3), since R, S, ΔS, Δr1, Δr2, and α are known values, β can be obtained. Therefore, X can be calculated by the following formula (4). Then, a table showing the relationship between α and X is created, and the feeding operation of the grinding wheel 28 is controlled according to this table.

The finish grinding process (after finishing the grinding process for Δr1) is performed under the conditions of the following formula (5). In equation (5), since R, r, S, .DELTA.S, .DELTA.r2, and .alpha. are known values, .beta. can be obtained. Therefore, X can be calculated by the following formula (6). Then, a table showing the relationship between α and X is created, and the feeding operation of the grinding wheel 28 is controlled according to this table.

Spark out after finish grinding (after grinding for Δr2) is performed under the following condition (7). In equation (7), since R, r, S, ΔS, and α are known values, β can be obtained. Therefore, X can be obtained by the following formula (8). Then, the feeding operation of the grinding wheel 28 is stopped at the position X to control the grinding process.

Next, the detailed operation of the grinding process (processing step) will be described with reference to the drawings. The control device 31 advances the master main shaft Cm (center 14) and the slave main shaft Cs (center 18) toward each other to pressurize and support the crankshaft W (step S11 in FIG. 4). Then, the control device 31 grips the crankshaft W with the chuck 15, controls each operation of the master servomotor 17, the slave servomotor 20 and the grinding wheel drive motor 27, and starts rotating the crankshaft W and the grinding wheel 28. (step S12 in FIG. 4).

The control device 31 controls the operation of the X-axis servomotor 25 to feed the grinding wheel 28 forward in the X-axis direction with respect to the crankshaft W at a rough grinding feed rate to start aerial grinding (step in FIG. 4). S13). During this time, the control device 31 reads a table showing the relationship between the phase α of the crank journal J3 corresponding to the crankshaft W to be ground and the feed position X of the grinding wheel 28 (step S14 in FIG. 4).

The control device 31 detects an AE wave generated by the grinding wheel 28 with a contact detection sensor (AE sensor) not shown, and determines whether or not the grinding wheel 28 has come into contact with the crankpin Pa1 (step S15 in FIG. 4). When the control device 31 determines that the grinding wheel 28 has come into contact with the crankpin Pa1, it controls the feeding operation of the grinding wheel 28 according to the read table to perform rough grinding (step S16 in FIG. 4). Finish grinding is performed (step S17 in FIG. 4), and further spark out is performed (step S18 in FIG. 4).

After the spark-out is completed, the control device 31 controls the operation of the X-axis servomotor 25 to start feeding the grinding wheel 28 backward in the X-axis direction with respect to the crankshaft W (step S19 in FIG. 4). Then, the control device 31 controls the operations of the master servomotor 17, the slave servomotor 20 and the grinding wheel drive motor 27 to stop the rotation of the crankshaft W and the grinding wheel 28 (step S20 in FIG. 4).

Then, the control device 31 releases the grip of the chuck 15, retreats the master spindle Cm (center 14) and the slave spindle Cs (center 18) in a direction away from each other, and removes the crankshaft W (step S21 in FIG. 4). . Then, the presence or absence of the next crankshaft W to be ground is confirmed (step S22 in FIG. 4). If there is no crankshaft W to be ground, all processing ends.

According to the grinder 1 of this embodiment, the feeding operation of the grinding wheel 28 is the amount of deformation of the crankshaft W after grinding, which is obtained from the correction amount B3 of the crankshaft W before grinding, that is, the amount of eccentricity of the crankpin P1. Since the control is performed based on the error ΔS, each crankshaft W can be accurately ground, and the grinding accuracy can be improved. Further, the crankshaft W has a plurality of grinding processing points P1-P4, and since each of the grinding processing sites P1-P4 can be subjected to rough grinding and finish grinding, the grinding efficiency can be improved.

(4. Overview of another grinding method)
Next, an outline of another grinding method in this embodiment will be described with reference to the drawings. Here, in this example, as in the grinding method described above, as shown in FIG. 9, the case where the crankpin P1 is ground by the grinding wheel 28 will be described. Note that the radius of the grinding wheel 28 is R, and the radius of the crank pin P1 after grinding indicated by the solid line in the drawing is r.

In this grinding control as well, it is necessary to vary the feed position of the grinding wheel 28, that is, the distance X between the rotation center Oj3 of the crank journal J3 and the rotation center Og of the grinding wheel 28 according to the phase α of the crank journal J3.

In FIG. 9, the center Opa1 of the crankpin Pa1 before grinding indicated by the one-dot chain line is the center Op1 of the crankpin P1 after grinding. It is assumed that the ground crankpin P1 is deviated in the direction of a straight line M3 connecting with the center Op1 by an amount of eccentricity error ΔS. The eccentricity of the crankpin P1 after grinding is S-ΔS.

The above items are the same as the grinding method described above, and the following items are different from the grinding method described above. That is, a straight line M4 connecting the rotation center Og of the grinding wheel 28 and the center Opa1 of the crank pin Pa1 before grinding is formed with respect to the straight line M1 connecting the rotation center Oj3 of the crank journal J3 and the rotation center Og of the grinding wheel 28. Let γ be the angle.

When set as described above, the grinder 1 controls the grinding of the crankpin Pa1 before grinding whose center is shifted by ΔS from the center Op of the crankpin P1 after grinding. In this case, as the grinding progresses, the radius of the crankpin Pa1 and the amount of eccentricity of the crankpin Pa1 change.

In this example, the radius of the crankpin Pa1 before grinding is set to r+Δr1+Δr2, and the amount of eccentricity is set to S at the beginning of the rough grinding process. , the radius of the crankpin Pa1 is set to r + Δr2, the eccentricity is set to S-ΔS1, and in the finish grinding, the radius of the crankpin Pa1 is set to r + Δr2, the eccentricity is set to S-ΔS2, and the finish grinding is performed. A case will be described where the radius of the crankpin Pa1 is set to r and the amount of eccentricity is set to S-.DELTA.S in the spark-out after the end (after the end of grinding for .DELTA.r2). ΔS1 and ΔS2 have a relationship of ΔS>ΔS2>ΔS1.

The initial stage of rough grinding in the grinding machine 1 (before grinding for Δr1) is performed under the conditions of the following equation (9). In equation (9), since R, S, ΔS, Δr1, Δr2, and α are known values, γ can be obtained. Therefore, X can be calculated by the following formula (10). Then, a table showing the relationship between α and X is created, and the feeding operation of the grinding wheel 28 is controlled according to this table.

The latter stage of the rough grinding process in the grinding machine 1 (after the end of the grinding process for Δr1) is performed under the conditions of the following equation (11). In equation (11), since R, S, ΔS, Δr2, and α are known values, γ can be obtained. Therefore, X can be calculated by the following formula (12). Then, a table showing the relationship between α and X is created, and the feeding operation of the grinding wheel 28 is controlled according to this table.

Finish grinding is performed under the conditions of the following formula (13). In equation (13), since R, r, S, ΔS, Δr2, and α are known values, γ can be obtained. Therefore, X can be obtained by the following equation (14). Then, a table showing the relationship between α and X is created, and the feeding operation of the grinding wheel 28 is controlled according to this table.

Spark out after finish grinding (after grinding for Δr2) is performed under the condition of the following equation (15). In equation (15), since R, r, S, ΔS, and α are known values, γ can be obtained. Therefore, X can be obtained by the following equation (16). Then, the feeding operation of the grinding wheel 28 is stopped at the position X to control the grinding process. This processing method can also provide the same effects as the processing method of the above-described embodiment.

(5. Others)
In the above-described embodiment, the storage device 33 is configured to store a table representing the relationship between the amount of correction and the amount of deformation. good.
In addition, although an in-line 4-cylinder single-plane crankshaft W has been described as an example of a workpiece, a double-plane crankshaft, an in-line 6-cylinder crankshaft, etc., or a cylindrical shaft other than the crankshaft W, a camshaft, etc. It is also applicable to

Further, although the grinder 1 is configured such that the master spindle Cm and the slave spindle Cs are rotationally driven, the grinder may be a grinder in which only the master spindle Cm is rotationally driven. Alternatively, a single head grinder may be used.

1: Grinder 12: Headstock 13: Tailstock 14, 18: Center 15: Chuck 17: Master servomotor (workpiece drive motor) 24: X-axis servomotor (feeder) 25 : Feed screw (feed device) 26: Grinding wheel head 27: Grinding wheel drive motor 28: Grinding wheel 31: Control device 32: Input device 33: Storage device W: Crankshaft P1-P4: Crank Pin, J1-J5: crank journal

Claims (5)

a grinding wheel table that rotatably supports a grinding wheel and has a grinding wheel drive motor that rotationally drives the grinding wheel;
a headstock that rotatably supports a workpiece and has a workpiece drive motor that drives the workpiece to rotate;
a feeding device for relatively moving the grinding wheel toward and away from the workpiece in a direction intersecting the rotation axis of the workpiece;
a control device for grinding the workpiece with the grinding wheel by controlling the feeding operation of the feeding device;
A grinding machine comprising
The control device is
The amount of correction at the processed portion of the workpiece when the bend of the workpiece before grinding that is bent in the direction intersecting the rotation axis of the workpiece is corrected, and the amount of correction at the processed portion of the workpiece after grinding an input device for inputting an eccentricity error with respect to the rotation axis of the workpiece ;
a storage device that stores the correlation between the input correction amount and the eccentricity error ;
With reference to the correlation, the eccentricity amount error of the machining portion of the workpiece to be currently ground corresponding to the input correction amount of the machining portion of the workpiece to be currently ground is obtained, and the eccentricity is obtained. By controlling the feeding operation of the feeding device in consideration of the amount error and the eccentricity phase from the rotation axis of the workpiece at the machining portion of the workpiece to be currently ground, the grinding wheel can be used to grind the current workpiece. Grinding machine that grinds the workpiece. the workpiece is a crankshaft comprising a crank journal and a crank pin ;
the crankshaft is bent in a direction that intersects the axis of rotation of the crankshaft;
2. The grinder according to claim 1 , wherein said processed portion is said crank pin . The control device obtains the distance between the rotation axis of the crankshaft and the rotation axis of the grinding wheel based on the distance between the center axis of the crankpin after grinding and the rotation axis of the grinding wheel, and calculates the feed rate. 3. Grinding machine according to claim 2 , which controls the feed movement of the device. The control device obtains the distance between the rotation axis of the crankshaft and the rotation axis of the grinding wheel based on the distance between the center axis of the crankpin and the rotation axis of the grinding wheel before grinding, and calculates the feed rate. 3. Grinding machine according to claim 2 , which controls the feed movement of the device. A grinding method for grinding a workpiece with a grinding machine,
The grinder is
a grinding wheel table that rotatably supports a grinding wheel and has a grinding wheel drive motor that rotationally drives the grinding wheel;
a headstock that rotatably supports a workpiece and has a workpiece drive motor that drives the workpiece to rotate;
a feeding device for relatively moving the grinding wheel toward and away from the workpiece in a direction intersecting the rotation axis of the workpiece;
a control device for grinding the workpiece with the grinding wheel by controlling the feeding operation of the feeding device;
with
The grinding method is
The amount of correction at the processed portion of the workpiece when the bend of the workpiece before grinding that is bent in the direction intersecting the rotation axis of the workpiece is corrected, and the amount of correction at the processed portion of the workpiece after grinding an input step of inputting an eccentricity error with respect to the axis of rotation of the workpiece ;
a storage step of storing the correlation between the input correction amount and the eccentricity error ;
With reference to the correlation, the eccentricity amount error of the machining portion of the workpiece to be currently ground corresponding to the input correction amount of the machining portion of the workpiece to be currently ground is obtained, and the eccentricity is obtained. By controlling the feeding operation of the feeding device in consideration of the amount error and the eccentricity phase from the rotation axis of the workpiece at the machining portion of the workpiece to be currently ground, the grinding wheel can be used to grind the current workpiece. A processing step for grinding the workpiece of
A grinding method comprising:

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