JPH07100760A - Grinding device - Google Patents

Abstract

PURPOSE:To improve the out of roundness, surface roughness and diameter precision of a ground surface without increasing the working cycle time and without increasing the dispersion of the working cycle time, as for a grinding device. CONSTITUTION:The first calculating means 140 calculates the cut-in quantity necessary for forming a ground surface Wa which is finishing-ground free from spark-out by a grinding wheel 19 to a true circle, and the second calculating means 150 calculates the forestage grinding completion diameter immediately before the true circle formation on the basis of the average cut-in quantity, final cut-in quantity for the ground surface and the target finished diameter, and the third calculating means 60 calculates the retreat quantity of a wheel spindle stock after the forestage grinding based on the position of the wheel spindle stock 13 corresponding to the forestage grinding completion diameter and the cut-in quantity. A control means 130 performs the forestage grinding by the wheel spindle stock up to the time when the outside diameter of the ground surface becomes equal to the forestage grinding completion diameter, and spark-out grinding is carried out after the stop by retreating the wheel spindle stock to a retreat position, and the wheel spindle stock is retreated again, and the finishing grinding is carried out.

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. 6, the centers 15a, 16 of the headstock and tailstock are used.
A grindstone base having a grinding wheel 19 that rotates with respect to the workpiece W supported by a is fed to grind the outer diameter of the surface to be ground. As shown by the line G in the diagram of FIG. 7, the position of the wheel head is
By feeding the rough grinding feed G1, the fine grinding feed G2, and the fine grinding feed G3 in this order while decreasing the feed speed, the outer diameter of the grinding surface Wa of the workpiece W can be expressed as a value converted into the wheel head position. For example, it decreases as shown by the line H. In this type of cylindrical grinding, the in-process sizing device 24 is used to obtain high accuracy and the outer diameter of the surface to be ground is measured during grinding. Is the target finish diameter D
At that point, the grinding process is completed without stopping the feed, and the wheel head is retracted as shown by the solid line G4.

[0003]

In this type of grinding apparatus, the cycle time varies due to the change in sharpness of the grinding wheel. This variation in cycle time has a large specific gravity in the fine grinding (and fine grinding) where the feed rate is low. Therefore, the rough grinding complete diameter and the fine grinding complete diameter are brought closer to the target finish diameter, and the fine grinding and fine grinding times are increased. Can be reduced by shortening. However, in such a case, the remaining amount of grinding is not sufficiently focused during the fine grinding, so that the surface roughness and roundness of the surface to be ground are reduced. In order to solve each of such problems, the pre-stage grinding completion diameter is calculated based on the finishing target diameter of the surface to be ground Wa, the fine grinding amount, and the feed amount for cutting, and the position of the wheel head corresponding to the pre-stage grinding completion diameter is calculated. The retracted position of the grinding wheel head is calculated based on the remaining amount of grinding required for finishing, and the grinding wheel wheel 19 grinds the grinding surface Wa until the outer diameter of the grinding surface Wa reaches the pre-stage grinding completion diameter. A grinding device has been developed in which the surface to be ground is ground by a grinding wheel after being rapidly retracted to a retracted position and then advanced at a fine grinding speed.

The shape of the surface to be ground Wa when it is rapidly retracted to the wheel head retreat position becomes a part of the spiral line as shown in FIG. 8, and when the grinding wheel 19 is advanced at a fine grinding speed in this state, The contact between the grinding surface Wa and the grinding wheel 19 becomes unstable,
There is a possibility that the workpiece W may shake. The present invention aims to solve each of these problems.

[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.
Position detecting means 110 for detecting the position of No. 3 and sizing means 120 for measuring the outer diameter of the surface Wa to be ground of the workpiece W during grinding.
And a first calculating means 140 for calculating the cutting amount of the grinding wheel 19 per one rotation of the workpiece, the cutting amount calculated by the first calculating means and the finishing cutting amount necessary for finishing the grinding surface Wa. And a second calculation means 150 for calculating the pre-stage grinding completion diameter immediately before being made into a perfect circle based on the target finishing diameter of the surface to be ground, and the grindstone base 13 corresponding to the pre-stage grinding completion diameter.
No. 3 and the third computing means 160 for computing the retracted position of the grindstone 13 based on the depth of cut computed by the first computing means 140, and the driving means 100 is operated to measure first by the sizing means 120. The grinding wheel base 13 is moved forward until the outer diameter of the surface to be ground Wa to be the pre-stage grinding complete diameter calculated by the second calculating means 150, and the surface to be ground Wa is finish ground by the grinding wheel 19, Spark grind is performed by retracting the grindstone 13 and stopping the grindstone 13 until the position detected by the position detector 110 reaches the retracted position calculated by the third calculator 160, and then the grindstone. The control means 130 for advancing 13 to perform finish grinding is provided.

[0006]

The control means 130 advances the grindstone base 13 through the driving means 100 to finish grind the ground surface Wa of the workpiece W by the grinding wheel 19, and to measure the ground surface Wa measured by the sizing means 120. When the outer diameter reaches the finish grinding completion diameter calculated by the second calculation means 150, the grindstone base 13 is retracted. At the time of this retreat, if the position of the grinding wheel base 13 detected by the position detection means 110 reaches the retracted position calculated by the third calculation means 160, the control means 130 stops the grinding wheel base 13 and sparks out by the grinding wheel 19. Grind. As a result, the surface to be ground Wa becomes a perfect circle having a diameter obtained by adding the finishing cut amount to the finishing target diameter, and the remaining amount of grinding caused by the bending of the workpiece W and its supporting portion due to grinding resistance is eliminated. If the grindstone base 13 is moved forward in this state, the surface to be ground Wa and the grinding wheel 19
The hitting is stable, and there is no fear that the workpiece W will shake.

[0007]

As described above, in the present invention, after the finish grinding, the grinding wheel head is retracted to the retracted position calculated by the third calculating means to perform the spark-out grinding, so that the surface to be ground has the target finish diameter. At the same time as making the diameter a true circle with the final depth of cut added, the remaining amount of grinding is eliminated, and in the subsequent finish grinding by advancing the grinding wheel head, the surface to be ground and the grinding wheel contact are stable, so that the deflection of the workpiece Does not occur. Also,
Since the amount of finish grinding is minimized, there is little variation in cycle time due to changes in the sharpness of the grinding wheel.

[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 and other data.

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 have the first to third computing means 1
40, 150 and 160 are respectively configured.

Next, the operation of the present embodiment configured as described above will be described with reference to the flow chart shown in FIG. 3 and FIGS.
It will be described with reference to the explanatory diagram shown in FIG. When the grinding device starts to operate according to a command from the input device 40, first, the grinding process according to the machining program shown in FIG. 3 is started. Grinding wheel 19
When the workpiece W supported by the headstock 14 and the tailstock 16 is rotated by the motor 18 at a predetermined speed, the numerical controller 30 first determines in step 10 that the grindstone 13 is rotated.
Is advanced at a rough-grinding feed speed set in advance to rough-grind the workpiece W. That is, the CPU 31 decodes the grindstone rough grinding feed command in the machining program and gives the command value to the pulse distribution circuit 34.
By applying a pulse signal sent from the servo motor 23 to the servo motor 23 via the drive circuit 41, the servo motor 23 is driven to perform rough grinding.

In this case, when the cutting feed is applied to the grindstone base 13, the cutting feed position of the grindstone mount 13 which changes from moment to moment is detected by the position detector 25, and the detected value is input to the CPU 31 via the sensor controller 42. To be done. The tracing stylus 34a of the sizing device 24 is engaged with the ground surface Wa of the workpiece W, whereby the outer diameter of the ground surface Wa is measured in-process, and the measured value is converted into a digital signal by the AD converter 35. It is converted and input to the CPU 31. The surface to be ground Wa measured by the sizing device 24 as rough grinding progresses
If the diameter reaches the predetermined rough grinding completion diameter D1, the CPU 31 determines in step 11 that the rough grinding is completed, and advances the control operation to step 12. CP in step 12
U31 calculates the finish grinding completion diameter by the following mathematical expression 1.

[0015]

[Formula 1] Finish grinding finish diameter (previous stage finish grinding diameter) = D + V + U2 where D: target finish diameter V: final depth of cut (in advance to increase the surface roughness of the grinding surface Wa that is a perfect circle to a target value) Depth of cut defined) U2: Depth of feed of the grinding wheel 19 per revolution of the workpiece (= finishing grinding speed F2 / rotating speed of the spindle 15 during finishing grinding)
S2) Here, D, V, F2, and S2 are from the input device 40 to the memory 3
It is the data stored in 2 and based on this data U2
Is calculated. This U2 is the value converted to diameter.

Next, in step 13, the CPU 31 advances the grindstone base 13 at a predetermined finishing grinding speed F2, which is slower than the rough grinding speed, and finishes the workpiece W. If the finish grinding progresses and the diameter of the surface to be ground Wa measured by the sizing device 24 reaches the finish grinding completed diameter calculated by the mathematical formula 1, the CPU 31 determines in step 14 that the finish grinding is completed and executes the control operation. Proceed to step 15.

The operation state in steps 10 to 14 will be described below with reference to FIG. In the figure, the solid line A indicates the grinding wheel base 13 detected by the position detector 25.
In the cutting feed position, the broken line B represents the diameter of the surface to be ground Wa detected by the sizing device 24 converted to the position of the grindstone base 13. It should be noted that the solid line A indicates that an error caused by thermal displacement between the workpiece W and the grinding wheel 19 and wear of the grinding wheel 19 is corrected by an appropriate means. Position detector 2 for rough grinding
The position of the grinding wheel base 13 detected by 5 decreases as shown by the line A1, the surface to be ground Wa is ground by the grinding wheel 19, and the diameter of the surface to be ground Wa measured by the sizing device 24 is the line. It decreases as shown in B1. During this period, the remaining amount of grinding due to the bending of the workpiece W and its supporting portion due to the grinding resistance increases rapidly as shown by the line C1. If the diameter of the surface to be ground Wa reaches a predetermined rough grinding completion diameter D1 and switching from rough grinding to finish grinding, the position of the wheel head 13 decreases at a slower speed than the line A1 as shown by the line A2, and The diameter of the surface Wa decreases as shown by the line B2, and the remaining grinding amount gradually decreases as shown by the line C2.

At the time when finishing grinding in steps 13 and 14 is completed, the measured value of the ground surface Wa by the sizing device 24 is D + V + U2, but the shape of the ground surface Wa is exaggerated as shown in FIG. It is part of the spiral. Further, in this state, the distance between the rotation axis O of the workpiece W and the grinding point of the grinding wheel 19 is (D + V) / 2, and the workpiece W is rotated in this state to form a perfect circle indicated by a broken line. The diameter of the workpiece W is D + V. The cut amount from the ground surface Wa in the case where the spiral ground surface Wa is a perfect circle shown by a broken line is a value that continuously decreases in the circumferential direction, but the maximum value thereof is the value in the illustrated embodiment. It is equal to the cutting feed amount U2 of the grinding wheel 19 per one revolution of the workpiece.

Returning to the continuation of the explanation of the flow chart of FIG. 3, in step 15, the CPU 31 calculates the retracted position of the grindstone base 13 after finish grinding in accordance with the following mathematical formula 2, and as shown by the line A3 in FIG. The whetstone base 13 is retracted to the position.

[0020]

[Equation 2] Retreat position = E−U2 / 2 However, E: The diameter of the surface to be ground Wa detected by the sizing device 24 at the time of completion of finish grinding shown in FIG.
Numerical value converted to the position of 3 Next, in step 16, the CPU 31 draws the line A4 in FIG.
As shown in, the grinding wheel base 13 is stopped for a predetermined time and spark-out grinding is performed. This predetermined time is a predetermined time such that the spark-out grinding is completed. By this spark-out grinding, the diameter of the surface Wa to be ground becomes a perfect circle, and at the same time, the position of the wheel head 13 is changed as shown by the line B4 in FIG.
Approach E-U2 / 2. That is, at the time when this step 16 is completed, the surface to be ground Wa becomes a true circle having a diameter obtained by adding the final cutting amount V to the target finishing diameter D, and the remaining grinding amount is the line of FIG.
It sharply decreases to 0 as shown in C4.

Next, the CPU 31 calculates the final depth of cut (finish depth of cut) in step 17, and then in step 18,
Then, the grinding wheel head 13 is moved forward at a predetermined slow grinding speed to perform the final cutting (finish grinding) on the surface Wa to be ground (Fig. 4).
Line A5). When the depth of cut detected by the position detector 25 based on the retracted position reaches the final depth of cut calculated in step 17, the CPU 31 determines in step 19 that the final depth of cut is complete, and the control operation is performed in step 2
Then, as shown by the line A6 in FIG. 4, the wheel head 13 is stopped for a predetermined time to perform spark-out grinding. This step 1
8 to 20, the diameter of the surface Wa to be ground decreases as shown by the lines B5 and B6 in FIG.
As shown in C6, it becomes 0 after a little increase. The final cut amount calculation in step 17 is performed by subtracting the target finishing diameter D from the diameter of the surface to be ground Wa measured by the sizing device 24 when step 16 is completed. The value V used in Expression 1 may be used as it is as the final cut amount, but if the value V calculated as described above is used, the error generated between steps 12 to 16 can be removed.

After step 20 is completed, in step 21, the CPU 31 checks whether or not the diameter of the grinding surface Wa measured by the sizing device 24 is within the permissible range from the finish target diameter D, and within the permissible range. If so, the control operation proceeds to step 22 and the grindstone base 13 is retracted (see line A7 in FIG. 4) to end the machining program shown in the flowchart in FIG. Surface to be ground in the dimension check of step 21
When the measured value of the Wa diameter is out of the allowable range, steps 17 to 20 are performed again and the dimension check of step 21 is performed again. If it is still out of the allowable range, an error is displayed and the operation is stopped. Or step 17
The operation may be stopped by displaying an abnormality without repeating steps to 20.

According to the above-described embodiment, since the grinding wheel base 13 is retracted to the predetermined position after the finish grinding to perform the spark-out grinding, the finish grinding is performed in order to avoid the increase of the cycle time and the variation of the cycle time. Even when the cutting feed amount is increased, the grinding surface Wa can be made to be a perfect circle having a diameter obtained by adding the final cutting amount to the finishing target diameter, and at the same time, the remaining grinding amount can be zero. Therefore, the roundness, surface roughness, and diameter accuracy of the surface to be ground can be improved by the final cutting and spark-out grinding that are subsequently performed. Further, since the surface to be ground Wa is made into a perfect circle by the spark-out grinding and the final cutting is performed, the contact between the surface to be ground Wa and the grinding wheel 19 is stable and the wobble of the workpiece W does not occur.

In the above-described embodiment, an example in which the final depth of cut is calculated and the final depth of cut is performed to perform spark-out has been described. However, the grinding stone head 13 until the finishing target diameter D is detected from the sizing device. May be advanced to make the final cut and the spark out may be omitted.

[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 machining program of the embodiment shown in FIG.

FIG. 4 is an explanatory view of the operation of the embodiment shown in FIG.

5 is an explanatory view showing a surface to be ground and its vicinity at the time of completion of finish grinding in the embodiment shown in FIG. 2. FIG.

FIG. 6 is a diagram showing a main part of an example of a grinding apparatus targeted by the present invention.

FIG. 7 is an explanatory diagram of an operation of an example of a conventional grinding device.

8 is an explanatory view showing a surface to be ground and its vicinity at the time when the grinding process of the grinding apparatus shown in FIG. 7 is completed.

[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 ... First computing means, 150 ... Second computing means, 1
60 ... Third computing 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. Position detecting means for detecting the position of the grindstone base with respect to the workpiece, sizing means for measuring the outer diameter of the surface to be ground of the workpiece during grinding, and the depth of cut of the grinding wheel per revolution of the workpiece And a first calculation means for calculating, and a perfect circle based on the depth of cut calculated by the first calculation means, the finish depth of cut required for finishing the surface to be ground, and the target finish diameter of the surface to be ground. Second computing means for computing the immediately preceding front-stage grinding completion diameter, the position of the grinding wheel head corresponding to the previous-stage grinding completion diameter, and the retreat position of the grinding wheel base based on the depth of cut calculated by the first computing means. Third computing means, and First, the driving means is operated to move the grinding wheel head forward until the outer diameter of the surface to be ground measured by the sizing means reaches the pre-stage grinding complete diameter calculated by the second calculating means, and the grinding wheel is used for grinding. Finish grinding of the ground surface, and then the wheel head is retracted until the position detected by the position detecting means reaches the retracted position calculated by the third calculating means, and the wheel head is stopped to perform spark-out grinding. Then, the grinding apparatus is provided with a control means for advancing the grindstone to perform finish grinding.