JPH07100762A - Grinding device - Google Patents

Abstract

PURPOSE:To reduce the dispersion of the working cycle time due to the change in the cutting performance of a grinding wheel, as for a grinding device. CONSTITUTION:A worked state calculating means 140 calculates a plurality of factors showing the worked state which changes according to the change in the cutting performance of a grinding wheel 19, and a forestage grinding completion diameter correcting means 150 performs correction so that the previously determined forestage grinding completion diameter is set close to the target finished diameter according to the degree of the excellent cutting performance of a grinding wheel through the fuzzy estimation, using a plurality of factors as input information. A control means 130 grinds a ground surface by the grinding wheel by advancing the wheel spindle stock 13 up to the time when the outside diameter of the ground surface Wa becomes equal to the forestage grinding completion diameter corrected by the forestage grinding completion diameter correcting means, and then the wheel spindle stock is advanced at a fine grinding speed, and the ground surface is ground by the grinding wheel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding device for grinding a cylindrical outer diameter of a workpiece.

[0002]

2. Description of the Related Art In a grinding machine such as a cylindrical grinder, as shown in FIG. 11, the centers 15a, 1 of the headstock and tailstock are used.
Grinding wheel 19 that rotates with respect to the workpiece W supported by 6a
The outer diameter of the surface to be ground is ground by sending in a grindstone stand having. As shown by the line G in the diagram of FIG. 12, the grindstone position is sequentially fed to the workpiece W by rough grinding G1, fine grinding G2, and fine grinding G3 while decreasing the feed speed.
If the outer diameter of Wa is represented by a value converted to the position of the grinding wheel head, it decreases as shown by a line H, for example. In this type of cylindrical grinding, in-process sizing device 2 is used to obtain high accuracy.
When the outer diameter of the surface to be ground Wa reaches the predetermined rough grinding completion diameter d1 and fine grinding completion diameter d2, which is performed while measuring the outer diameter of the surface to be ground during grinding using 4, The feed rate is switched from coarse to fine feed and from fine to fine feed, and if the finishing target diameter D is reached, the grinding process is completed, spark-out grinding is performed as necessary, and the grinding head is moved. It is retreating. The difference between lines G and H at some point is
It is the deflection (remaining amount of grinding) of the workpiece and its supporting portion for giving the grinding resistance necessary for grinding.

[0003]

However, the relationship shown in FIG. 12 differs depending on the sharpness of the grinding wheel 19. That is, when the grinding wheel 19 has a good sharpness (for example, immediately after truing), as shown by the lines Ga and Ha in FIG. 13, since the remaining amount of grinding is small, the rough grinding completion diameter d1 is reached relatively early. As a result, the rough grinding feed of the wheel head becomes shorter, and the fine grinding and the fine grinding feeding with a low feed speed become longer accordingly. Therefore, the total time for grinding one workpiece, that is, the cycle time is long. Become. On the contrary, when the sharpness of the grinding wheel 19 becomes poor (for example, after processing a considerable number of workpieces after truing), the rough grinding feed becomes long, and the deflection of the workpiece W caused by this causes rough grinding and Since the fine grinding feed becomes shorter, the cycle time becomes shorter as shown by the lines Gb and Hb in FIG. That is, the cycle time varies depending on the sharpness of the grinding wheel. In the case of machining a workpiece on a continuous machining line, if there is such variation in some machining stations, it becomes a neck of the whole machining line and the efficiency of the machining line is lowered, which is not preferable.

An object of the present invention is to solve such a problem by correcting the diameter at the time of completion of pre-stage grinding such as rough grinding and fine grinding according to the sharpness of the grinding wheel.

[0005]

To this end, the grinding apparatus according to the present invention, as shown in FIG. 1, has a grinding wheel base 13 having a grinding wheel 19 which is rotationally driven by a motor, the grinding wheel 19 and the grinding wheel 19 thereby. Driving means 100 for relatively moving the grindstone base 13 and the workpiece W in a direction in which the workpieces W to be ground come close to and away from each other, and the grindstone base 1 for the workpiece W.
The position detecting means 110 for detecting the position of No. 3 and the sizing means 120 for measuring the outer diameter of the surface to be ground Wa of the workpiece W during grinding are provided, and the surface to be ground is subjected to fine grinding subsequent to the pre-stage grinding. In a grinding device having a finishing target diameter of Wa, a processing state calculation means 140 for calculating a plurality of factors indicating a processing state that changes in association with a change in sharpness of the grinding wheel 19, and the plurality of factors as input information. When the sharpness of the grinding wheel is good by fuzzy reasoning, the pre-stage grinding completion diameter correcting means 150 for correcting the pre-stage grinding completion diameter determined in advance according to the degree of the sharpness to the target finish diameter, and the driving means 10
When the outer diameter of the surface to be ground Wa measured by the sizing means 120 is operated 0, the outer diameter of the ground surface Wa is corrected by the pre-stage grinding completion diameter correcting means 15
The grinding wheel base 13 is moved forward at the front-stage grinding speed until the front-stage grinding complete diameter corrected by 0 is reached, the surface to be ground Wa is ground by the grinding wheel 19, and then the grinding wheel base 13 is moved forward at the fine grinding speed. A control means 130 for grinding the surface Wa to be ground by the grinding wheel 19 is provided.

[0006]

When the grinding wheel is sharp, the pre-stage grinding completion diameter correction means 150 is predetermined according to the degree of sharpness of the grinding wheel by fuzzy reasoning using a plurality of factors calculated by the processing state calculation means 140 as input information. Correct the front-stage grinding completion diameter so that it is close to the finishing target diameter. Control means 130
First, the grinding wheel base 13 is advanced at a relatively high cutting feed rate through the driving means 100, and the workpiece W is moved by the grinding wheel 19.
The outer diameter of the surface Wa to be ground, which is measured by the sizing means 120, is the front-stage grinding completion diameter correction means 15
When the pre-stage grinding completion diameter corrected by 0 is reached, the pre-stage grinding is terminated. Subsequently, the control means 130 switches the cutting feed speed to a relatively low fine grinding speed and advances the grindstone base 13 to finely grind the surface Wa to be ground. When the outer diameter of the surface to be ground Wa measured by the sizing means 120 reaches the finishing target diameter, the control means 130 performs spark-out grinding as necessary, retracts the wheel head 13, and finishes the grinding.

[0007]

As described above, according to the present invention, when the grinding wheel has a good sharpness, the pre-stage grinding is performed up to the pre-stage grinding completion diameter corrected so as to approach the finishing target diameter. Small fine grinding feeds will not be long and therefore cycle times will not be long. As a result, the variation in cycle time is reduced and the average cycle time is also reduced as compared with the conventional case.

[0008]

EXAMPLES The present invention will be described below with reference to examples shown in FIGS. As shown in FIG. 2, a headstock 14 and a tailstock 16 for bearing a main spindle 15 and a tailstock 16 are placed on the left and right sides of a worktable 12, which is guided and supported on a bed 11 of a grinding machine 10 so as to be movable in the left-right direction (Z direction). The workpiece W is coaxially provided so as to be opposed to each other in the direction of the center 1 provided on the spindle 15 and the tailstock 16.
Both ends are supported by 5a and 16a. The spindle 15 is rotationally driven by a motor 18 provided on the spindle stock 14, and the workpiece W has a left end portion protruding from the spindle 15 to prevent the detent member 1 from rotating.
7 and is rotated together with the main shaft 15.

A grindstone base 13 is guided and supported on the bed 11 so as to be movable in a horizontal X direction orthogonal to the Z direction, and a grindstone wheel 19 such as a CBN grindstone is parallel to the spindle 15 on the grindstone base 13. It is supported by a simple grindstone shaft 20 and is rotationally driven by a motor 22 via a V-belt rotation transmission mechanism 21. The servomotor 23 provided in the bed 11 is controlled and driven by a drive circuit 41 that operates based on a control pulse distributed from the pulse distribution circuit 34 of the numerical controller 30, and the grindstone base 13 is driven via a feed screw device (not shown). To feed in the X direction. Position detector 2 such as encoder
Reference numeral 5 detects the moving position of the grindstone 13 via the rotation angle of the servomotor 23, and the detected value is the sensor controller 4
It is input to the numerical control device 30 via 2.

The in-process sizing device 24 installed on the workpiece table 12 engages the tips of the pair of measuring elements 34a with the surface to be ground Wa of the workpiece W being ground to measure its outer diameter. Continuously and directly, and the measurement signal (analog signal)
Is input to the numerical controller 30.

As shown in FIG. 2, the numerical control device 30 has a
Central processing unit (CPU) that controls and manages the entire grinding machine
3, a memory 32, an interface 33 for exchanging data with the outside, and a pulse distribution circuit 34 for distributing and transmitting drive pulses in response to a command from the CPU 31. To the CPU 31, the sizing device 24 is connected via the A / D converter 35, and the sensor controller 42 is connected. This sensor controller 42 is a CPU
The position detector 25 is connected to the position detector 25 described above. Further, the interface 33 is connected to an input device 40 such as a keyboard for inputting control data and the like, and the pulse distribution circuit 34 is connected to the servo motor 23 described above via a drive circuit 41. The memory 32 stores a machining program for machining the workpiece W, a program for correcting the grinding completion diameter, membership functions and production rules for executing fuzzy inference, and other data. Has been done.

In the relationship between this embodiment and the claims, the servo motor 23 is the driving means 100, the position detector 25 is the position detecting means 110, and the sizing device 24 is the sizing means 120.
The CPU 31 and the pulse distribution circuit 34 are control means 130.
The CPU 31 and the memory 32 are the processing state calculating means 14
0 and pre-stage grinding completion diameter correcting means 150 are respectively configured.

Next, the operation of the present embodiment configured as described above will be described. When the grinding device starts operating in response to a command from the input device 40, the CPU 3 of the numerical control device 30
1 is a state in which the grinding wheel 19 is rotated and the workpiece W supported by the headstock 14 and the tailstock 16 is rotated at a predetermined speed by the motor 18 based on a main machining program (not shown). The grindstone base 13 is moved forward at the rough grinding feed speed, and the rough grinding of the workpiece W is performed. The cutting feed position of the grindstone 13 that changes from moment to moment during rough grinding is detected by the position detector 25, and the detected value is input to the CPU 31 via the sensor controller 42, and the sizing device 24 operates the probe 34a. The outer diameter of the surface to be ground Wa engaged with the surface to be ground Wa of the object W is measured in-process, and the measured value is A-
The digital signal is converted by the D converter 35 into a CPU
It is input to 31.

When the rough grinding progresses and the diameter of the surface to be ground Wa measured by the sizing device 24 reaches the rough grinding completion diameter D1, CP
U31 switches the cutting feed rate to a preset fine-grinding feed rate that is smaller than the rough-grinding feed rate and advances the grindstone base 13 to perform fine-grinding of the workpiece W. When the fine grinding progresses and the diameter of the surface to be ground Wa measured by the sizing device 24 reaches the fine grinding completed diameter D2, the CPU 31 switches the cutting feed speed to a smaller fine feed speed set in advance to change the grinding wheel head. 13 is advanced to perform fine grinding of the workpiece W.
When the diameter of the surface to be ground Wa measured by the sizing device 24 reaches the finishing target diameter D, the CPU 31 stops the feed of the grindstone 13, performs spark-out grinding for a predetermined time, and then retracts the grindstone 13. Then, the grinding of the workpiece W is completed, and the next workpiece W is continuously processed.

The operation of the present embodiment described above is substantially the same as the operation of the prior art shown in FIG. 12 except that the rough grinding completion diameter D1 and the fine grinding completion diameter D2 are corrected according to the grinding state. It is the same. The grinding wheel 19 has its grinding surface shaped by truing every time a predetermined number of workpieces W are machined, and the number of workpieces W after truing is stored in the memory 32.
Memorized in.

In this embodiment, the grinding completion diameter correction process shown in the flowchart of FIG. 3 is performed between the rough grinding and the fine grinding described above. When rough grinding is started, this grinding completion diameter correction processing is started in parallel with this. First, in step 100 and step 101 of FIG. 3, the CPU 31 inputs the diameter of the surface to be ground Wa measured by the sizing device 24 and the position of the wheel head 13 detected by the position detector 25.
It is assumed that the position of the grinding wheel base 13 is corrected for the error caused by the thermal displacement between the workpiece W and the grinding wheel 19 and the abrasion of the grinding wheel 19. In subsequent step 102, the CPU 31 calculates the remaining grinding amount Z as the difference between the input diameter of the surface to be ground Wa and the position of the grindstone base 13 (value converted to the diameter of the surface to be ground Wa).

Next, in step 103, the CPU 31 compares the position of the grinding wheel base 13 input in step 101 with a predetermined designated position and determines whether to correct the rough grinding completion diameter. If the grinding wheel head 13 has not reached the designated position, the CPU 31 repeats steps 100 to 102, and if it reaches the designated position, advances the control operation to step 104. This designated position is set to a position where the rough grinding progresses to a certain extent and the grinding state is stable, and even before the grinding wheel 19 has the worst sharpness, it does not switch to the fine grinding before that. In this embodiment, the correction of the rough grinding completion diameter is performed when the position of the grindstone base 13 reaches a predetermined designated position. However, the diameter of the grinding surface Wa input in step 100 is It may be performed when the designated diameter is determined in advance.

When the grindstone base 13 reaches the designated position, the CPU
31 indicates that the control operation proceeds to step 104 and the machining number ratio N
Is calculated. This machining number ratio N is the number of machining of the workpiece W after truing divided by the total number of machining performed during the truing interval. In the following step 105, the CPU 31 calculates the rough grinding completion diameter correction rate R by fuzzy reasoning based on the machining number ratio N and the remaining grinding amount Z calculated in step 102. The contents of this fuzzy reasoning are as follows.

First, in the memory 32 of the grinding apparatus of this embodiment, the input information membership function relating to the remaining grinding amount and the ratio of the number of machining shown in (a) and (b) of FIG. 4 and the output information membership shown in FIG. The functions and the production rules for rough grinding and fine grinding shown in FIGS. 6A and 6B are stored. Input information relating to remaining grinding amount and number of processed lines The horizontal axis of the membership function represents the remaining amount of grinding and the number of processed lines, and the vertical axis represents grades from 0 to 1. SML, M
DL and LRG are functions that represent changes in the grade with respect to the remaining amount of grinding, which is considered to be small, medium, and large, and the ratio of the number of processed lines. The horizontal axis of the output information membership function represents the correction factor, and the vertical axis represents the grade from 0 to 1. NLG, NML, NSL ... Are functions selected by the production rule, and the correction factor is calculated from the area centroid of the function truncated from the grade. CPU31
First, the grade is calculated based on the remaining grinding amount Z calculated in step 102 and the membership function of the remaining grinding amount. In the illustrated example, as shown in (a) of FIG. 4, the grade of the remaining amount of grinding is 0.4 for SML and for MDL.
Calculated as 0.6. Similarly, the grade for the number of processed lines is calculated as 0.2 for ZRO and 0.8 for SML. Applying these numerical values to the production rule for rough grinding in FIG. 6 (a) and taking MIN, the result is as shown in FIG. 7. Based on this, three functions of the output information membership function are truncated, The correction factor R is calculated by the CPU 31 from the center of gravity of the area obtained by combining the shaded portions of the three functions. As a result, the correction rate R is calculated to be 52%.

Next, in step 106, the CPU 31 determines a predetermined reference rough grinding completion diameter and a finish target diameter D.
The difference between and is multiplied by a correction factor R and added to the finishing target diameter D to calculate the rough grinding completion diameter D1, and the grinding completion diameter correction processing in rough grinding is completed. Rough grinding by the main machining program being performed in parallel progresses and the sizing device 2
When the diameter of the surface to be ground Wa measured by 4 reaches the rough grinding completion diameter D1 corrected as described above, the CPU 31 switches the cutting feed speed from the rough grinding feed speed to the fine grinding feed speed and the grinding wheel head. 13 is advanced and the fine grinding of the workpiece W is started. If the remaining amount Z of grinding is small, the ratio N
If the value is small, the sharpness of the grinding wheel 19 is good, so the correction factor R
Becomes smaller as the sharpness of the grinding wheel 19 becomes better, and the rough grinding completion diameter D1 also becomes smaller to approach the finishing target diameter D.

Also in the fine grinding which is continuously performed by the main machining program, the grinding completion diameter correction process is performed in parallel with the fine grinding according to the flowchart of FIG. 3, as in the case of the rough grinding. In this case, as shown in (b) of FIG. 6, the production rule is slightly different from that in the case of rough grinding, but except for this, the CPU 31 similarly calculates the correction rate R, and the correction rate R is calculated in advance. Based on the established standard fine grinding completion diameter,
The fine grinding completion diameter D2 is calculated in the same manner as in the case of rough grinding.
The fine grinding performed in parallel progresses, and the diameter of the grinding surface Wa measured by the sizing device 24 is the corrected fine grinding completed diameter.
When reaching D2, the CPU 31 switches the cutting feed rate from the fine grinding feed rate to the fine grinding feed rate, advances the grinding wheel base 13, and starts fine grinding of the workpiece W. As in the case of rough grinding, the correction factor R during fine grinding becomes smaller as the sharpness of the grinding wheel 19 becomes better, and the fine grinding completion diameter D2 also becomes smaller and approaches the finishing target diameter D.

In fine grinding, if the diameter of the surface to be ground Wa measured by the sizing device 24 reaches the finishing target diameter D, C
The PU 31 finishes the grinding process of the workpiece W as described above, and processes the next workpiece W.

As described above, according to this embodiment, when the sharpness of the grinding wheel 19 is good immediately after truing,
In the rough grinding, the grinding is performed up to the rough grinding completion diameter D1 that is corrected so as to approach the target finishing diameter D, and in the fine grinding, the fine grinding completion diameter D2 that is corrected so as to approach the target finishing diameter D is performed. The fine-grinding feed having a low feed speed does not become longer than that when the grinding wheel 19 has poor sharpness. Therefore, the cycle time when the sharpness of the grinding wheel 19 is good is not longer than that when the sharpness is poor,
The variation in cycle time is reduced and the average cycle time is also reduced as compared with the conventional one. It should be noted that the output information membership function shown in FIG. 5 should be approximately left-right symmetric with 100% in the vicinity of the center so that a reasonable output value can be obtained.
It does not necessarily have to be 0%.

The input information for the fuzzy inference in step 105 uses the remaining grinding amount and the ratio of the number of machining lines in the above-mentioned embodiment. The correction factor R may be calculated. The amount of change in the remaining grinding amount is the amount of change in the remaining amount of grinding per one revolution of the workpiece calculated by using a large number of continuously stored remaining amounts of grinding. For this calculation, step 1 in FIG.
In 02, the remaining grinding amount calculated at a predetermined small time interval is stored in advance in the storage area of the memory 32 by the number corresponding to two rotations of the workpiece. The input information membership function of the remaining amount of grinding change is as shown in FIG. 8, the production rules for rough grinding and fine grinding are as shown in (a) and (b) of FIG. 9, and the other members are the same. The ship function is the same as in the previous embodiment.

Further, as input information for fuzzy inference, in addition to the remaining grinding amount, the number of machining lines and the remaining grinding amount change amount used in each of the above-mentioned embodiments, the remaining grinding velocity ratio, the remaining grinding fluctuation amount, etc. What changes in relation to the sharpness of the grinding wheel 19 can be used. The remaining speed ratio of grinding is step 10
It is obtained by dividing the grinding residual amount calculated in 2 by the cutting speed per one rotation of the workpiece, and the input information membership function of this grinding residual velocity ratio is as shown in FIG. The amount of remaining grinding amount is the difference between the maximum value and the minimum value of the remaining amount of grinding per one revolution of the workpiece, calculated using a large number of remaining grinding amounts stored in the storage area. The information membership function is as shown in FIG. When these input information items are used, the production rule is set such that the smaller the negative residual grinding amount variation amount is, the smaller the grinding residual amount deviation amount is, and the smaller the correction rate R is. To create. This input information is 2
Not limited to one, three or more may be used in combination.

In the above embodiment, the pre-grinding performed before the fine grinding as the final finishing is divided into the rough grinding and the fine grinding, but the fine grinding may be omitted depending on the grinding conditions. You may implement.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a grinding apparatus according to the present invention.

FIG. 2 is a diagram showing an overall configuration of an embodiment of a grinding apparatus according to the present invention.

FIG. 3 is a flowchart showing a subprogram of a grinding completion diameter correction process in the embodiment shown in FIG.

FIG. 4 is a diagram showing an example of an input information membership function used for fuzzy inference of a correction factor.

FIG. 5 is a diagram similarly showing an example of an output information membership function.

FIG. 6 is a diagram similarly showing an example of a production rule.

7 is a diagram showing an example in which actual numerical values are applied to the production rule of FIG.

FIG. 8 is a diagram showing another example of the input information membership function.

FIG. 9 is a diagram showing another example of the production rule, which corresponds to FIG. 8;

FIG. 10 is a diagram showing still another example of the input information membership function.

FIG. 11 is a diagram showing a main part of an example of a grinding apparatus targeted by the present invention.

FIG. 12 is an explanatory diagram of a basic operating state of an example of a conventional grinding device.

FIG. 13 is a diagram illustrating a difference in operation due to a difference in sharpness of a grinding wheel in a conventional grinding device.

[Explanation of symbols]

13 ... Grinding stone base, 19 ... Grinding wheel, 100 ... Driving means, 11
0 ... Position detecting means, 120 ... Sizing means, 130 ... Control means, 140 ... Machining state calculating means, 150 ... Pre-stage grinding completion diameter correcting means, W ... Workpiece, Wa ... Surface to be ground.

Claims (1)

[Claims] 1. A grindstone base having a grindstone wheel driven to rotate by a motor, and a drive means for relatively moving the grindstone base and the workpiece in a direction in which the grindstone wheel and a workpiece ground by the grindstone move toward and away from each other. A position detecting means for detecting the position of the grindstone with respect to the workpiece and a sizing means for measuring the outer diameter of the surface to be ground of the workpiece during grinding, and performing fine grinding subsequent to the pre-stage grinding, In a grinding device having a surface to be ground as a finishing target diameter, a processing state calculating means for calculating a plurality of factors indicating a processing state that changes in association with a change in sharpness of the grinding wheel, and the plurality of factors as input information. When the sharpness of the grinding wheel is good by fuzzy reasoning, a pre-stage grinding completion diameter correction means for correcting the pre-stage grinding completion diameter predetermined according to the degree to approach the finishing target diameter,
By operating the driving means, first, the wheel head is advanced at the pre-stage grinding speed until the outer diameter of the surface to be ground measured by the sizing means reaches the pre-stage grinding complete diameter corrected by the pre-stage grinding completion diameter correcting means. And a grinding means for grinding the surface to be ground by the grinding wheel, and then advancing the grinding wheel base at a fine grinding speed to grind the surface to be ground by the grinding wheel.