JPH0639712A - Numerically controled grinder - Google Patents

Abstract

PURPOSE:To provide a numerical controlled grinder capable of performing efficient grinding work and also improving grinding accuracy. CONSTITUTION:Grinding remaining quantity DELTA, an index for grinding condition, is calculated with a grinding remaining quantity operation means 360, a maximum speed, allowing delivering a wheel spindle stock corresponding to the grinding condition of a grinding wheel, is calculated with a maximum allowable speed operation means 364 based on this grinding remaining quantity, and a present delivering speed for the wheel spindle stock is changed so as to become the allowable maximum speed with a speed change means 370. Maximum remaining quantity, at a point of time, when sparking-out, obtained from desired shape accuracy by sparking-out for a fixed time, is started, is calculated based on the grinding remaining quantity DELTA with a maximum remaining quantity allowable value operation means 368. Grinding is performed with grinding to this maximum remaining quantity detected with a sparking-out means 372.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerically controlled grinding machine, and more particularly to a device for adaptively controlling the feed speed of a wheel head and the maximum remaining amount at the start of spark out.

[0002]

2. Description of the Related Art Conventionally, in a grinding process using a grinder, an operator sets or automatically determines processing conditions such as a work speed and a wheel head feed speed so as to satisfy a required processing result. There is. In this way, the feed (cutting) of the grindstone base with respect to the workpiece is controlled based on the speed set in advance before processing. Sparking out in the grinding process is performed in order to eliminate the error between the workpiece diameter calculated from the feed amount of the grinding wheel head and the actual workpiece diameter due to the deflection of the workpiece that occurs when grinding the workpiece. When the diameter of the object is measured with a sizing device and the size reaches a predetermined value, the feed of the grinding wheel head is stopped and started.

[0003]

By the way, in the grinding process of a grinding machine, the grinding state changes from moment to moment depending on the present diameter of the workpiece, the sharpness of the grindstone and the surrounding environment. For this reason, even if the same workpiece is ground under the same conditions, there are problems that variations in the grinding accuracy may occur for each workpiece and that the grinding dimension may fall outside the allowable range. As a countermeasure for this, it is possible to set the processing conditions in advance assuming the worst case as described above, but there is a problem that the processing time becomes long as a result. There is also a problem associated with spark out. For this explanation, the NC program of the wheel head feed is shown in FIG. 9, and the grinding work based on this program is shown in FIGS.
Shown in. In the figure, the vertical axis represents the wheel head position X and the horizontal axis represents the time t.
And the solid line represents the NC program and the dash-dotted line represents the workpiece diameter. In this program, the grindstone is fed by the coarse grinding feed (relatively high feed speed) until time a, then the fine grinding feed (relatively slow feed speed) by time b, and stopped at time b. Start sparking out,
Continue sparking out until the desired final dimension ΔMIN is achieved. As mentioned above, the grinding condition is changing,
For example, as shown in FIG. 10, when the sharpness of the grindstone is poor and the sparkout is started from the time b, the sparkout is continued until the desired final dimension ΔMIN is obtained (c ′). The time is longer (corresponding to c to c ') than the standard one. Furthermore, an abnormality may be detected due to time-out. On the contrary, as shown in the example of FIG. 11, when the grindstone is well cut off and the sparkout is started from the time b and the desired final dimension ΔMIN is obtained early (time c ″), the sparkout time is insufficient and the desired final dimension ΔMIN is obtained. In some cases, the shape accuracy (surface roughness, circularity) cannot be obtained.In the example of FIGS. However, as another method, set the workpiece diameter at the completion of cutting to start spark out, detect this with the sizing device, and stop the grindstone feed at this point to stop spark out. Even if it is started and then the sparkout is ended by detecting the final dimension ΔMIN, the same problem as in FIGS. 10 and 11 is caused.

The present invention has been made to solve the above problems, and an object of the present invention is to perform efficient grinding and improve grinding accuracy.

[0005]

SUMMARY OF THE INVENTION The structure of the invention for solving the above-mentioned problems is a numerical control for machining a work piece by moving a grindstone base on which a grindstone is supported with respect to a work piece at a predetermined feed speed. In a grinding machine, a sizing device for measuring the outer diameter dimension of the workpiece, and grinding for calculating the remaining amount of grinding based on the outer diameter dimension of the workpiece measured by the sizing device and the whetstone position. A remaining amount calculating means, a remaining amount coefficient calculating means for obtaining a remaining amount coefficient representing a grinding condition based on the grinding remaining amount and the feed rate of the grinding wheel head, and a sparkout start based on a predetermined sparkout time. Maximum remaining amount allowable value calculating means for calculating an allowable value of the maximum remaining amount at the time point, speed changing means for changing the current feed speed based on the grinding remaining amount and the maximum remaining amount allowable value, and Grinded to the maximum remaining amount Characterized in that and a spark-out means for performing a spark-out is detected that.

[0006]

According to the above-mentioned means, the outer diameter of the workpiece measured by the sizing device, the outer diameter of the workpiece calculated from the position of the wheel head, the diameter of the whetstone, and the position of the spindle center supporting the workpiece. Is calculated as the remaining amount of grinding. And
Based on the remaining grinding amount and the current feed speed, the remaining amount coefficient indicating the sharpness of the grindstone is obtained, and the desired remaining shape factor is obtained according to the grinding state of this grindstone and the sparkout for a fixed time to obtain the desired shape accuracy. The maximum remaining grinding amount that can be obtained at the start of spark out is calculated. Further, the speed is calculated from the maximum grinding residual amount allowable value and the grinding residual amount. Then, the feed rate of the wheel head is changed so as to reach this rate. Then, it is detected that the maximum remaining amount has been ground, and spark-out is performed. In this way, the feed rate of the grinding wheel head in the grinding process is controlled so as to be always optimal, and the desired shape accuracy is obtained by sparking out.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing the overall configuration of a numerically controlled grinding machine according to the present invention. A table 52 that slides on the bed 51 of the grinder 50 is provided on the bed 51. The table 52 is moved in the horizontal direction in the drawing by driving the table feed motor 53. A headstock 54 and a tailstock 56 are mounted on the table 52.
Also, a sizing device 40 for measuring the outer diameter of the workpiece W is provided, the headstock 54 has a headstock 55, and the tailstock 5
6 has a tailstock shaft 57.

The workpiece W is pivotally supported by a main shaft 55 and a tailstock shaft 57, and is rotated by the rotation of the main shaft 55. The rotation of the spindle 55 is generated by the spindle motor 5 arranged on the spindle stock 54.
9 is performed. On the other hand, a grinding wheel 60 for grinding the workpiece W is rotatably supported on a grinding wheel base 61, and is rotationally driven by a grinding wheel drive motor 62.
Further, the grindstone base 61 is controlled to move in the vertical direction in the drawing by a grindstone base feeding motor 63. Table feed motor 5
3. The wheel head feed motor 63 is composed of a servo motor, and a numerical controller 30 is provided for numerically controlling these.

As shown in FIG. 2, the numerical controller 30 mainly has a CPU 31 and an R storing a control program.
OM32, RAM33 and input / output interface 34
And a pulse distribution circuit 35. CPU
The operation panel 2 is connected to the control panel 31 via the input / output interface 34.
0 is attached. On the operation panel 21 of the operation panel 20, a keyboard 22 for inputting data and a CRT display device 23 for displaying data are provided.
Further, the sizing device 40 is connected to the CPU 31 via the A / D conversion device 356, and the pulse distribution circuit 3
5 are connected to drive the table feed motor 53 and the wheel head feed motor 63, respectively.
Are connected to the pulse distribution circuit 35.

In the RAM 33, an NC data area 331 for storing NC data, a feed speed setting area 332 for setting the feed speed of the grinding wheel base 61, and a grinding wheel diameter storage area for storing the current grinding wheel diameter of the grinding wheel 60. 333 and sizing device 40
Sizing value storage area 334 for storing the diameter of the workpiece W measured by the following, a grinding residual quantity storage area 335 for storing a grinding residual quantity to be described later, and a spark-out time storage area for storing a set spark-out time. 336, a maximum remaining amount allowable value storage area 337 that stores an allowable value of the maximum remaining amount at the start of spark out, and a maximum allowable speed storage area 338 that stores the maximum allowable value of the feed speed of the grinding wheel head. Has been done.

Next, the CPU 3 of the numerical controller according to the present embodiment.
The function of No. 1 will be described with reference to the block diagram of FIG. 3 and FIG. 4 showing the relationship between the grindstone diameter and the sizing value during grinding. First, the outer diameter dimension 2RW of the workpiece W measured during the grinding process is measured by the sizing device 40 of FIG. 4, and this is input to the A / D conversion device 356 via the line 352 of FIG. And is read by the sizing measurement value input means 358. The sizing measurement value input means 358 sets the input value to R as a sizing value RW which is the radius of the workpiece W.
It is stored in the fixed size storage area 334 of the AM 33.

On the other hand, the distance from the center of rotation of the spindle, which is the mounting center of the workpiece W during grinding, to the center of the grinding wheel 60 mounted on the grinding wheel base 61 (grinding wheel position) G.
P is obtained from the signal output from the encoder 64 coaxially attached to the wheel head feed motor 63, and is read into the wheel head position input means 354 via the line 350 of FIG. 3, and this value is calculated as the remaining grinding amount calculation. It is output to the means 360. Then, the remaining grinding amount calculation means 360 calculates the remaining grinding amount Δ. The remaining grinding amount calculation means 360 calculates the radius dimension RW of the workpiece W stored in the fixed dimension storage area 334 of the RAM 33 and the radius RG of the grinding wheel 60 prestored in the grinding wheel diameter storage area 333 of the RAM 33. By adding and subtracting the grinding wheel head position GP input from the grinding wheel position input means 354, the remaining grinding amount Δ is obtained as shown in the following formula 1, and the value of this remaining grinding amount is stored in the remaining grinding amount storage area of the RAM 33. 335
To memorize. Δ = (RW + RG) -GP ... Equation 1

Next, the remaining amount coefficient calculating means 362 calculates the remaining amount based on the following expression 2 based on the remaining amount Δ of grinding and the feed rate V of the grinding wheel head stored in the feed rate setting area 332 of the RAM 33. The quantity coefficient η is calculated. It can be considered that the remaining coefficient η represents the state (sharpness) of grinding by the grindstone. η = f (Δ, V) Equation 2 = Remaining amount of grinding / Feed amount per one revolution of work piece = Δ × S / V where S is the spindle rotational speed Next, the maximum remaining amount allowable value calculation means 368 The maximum remaining amount allowable value ΔMAX at the start of spark out is defined as a function of this remaining amount coefficient η, the remaining amount (allowable dimensional error) ΔMIN finally allowed at the end of grinding, and the spark out time T. Then, it is obtained from the following Equation 3. In the present invention, since the spark-out time T is set to a preset constant time, the maximum remaining amount allowable value ΔMAX is set so that a desired shape accuracy can be obtained at this spark-out time T depending on the condition of the grindstone. It is calculated. The calculated value is stored in the maximum remaining amount allowable value storage area 337 of the RAM 33, and is also used for the workpiece diameter check for starting the spark out by the spark out means 372 described later. ΔMAX = f (ΔMIN, η, T) ··· Equation 3 = ΔMIN / (n / (1 + n)) ⁿ where n = spark-out speed = T × S

Next, the maximum permissible speed calculation means 364 determines the maximum permissible speed VMAX, which is the maximum permissible value of the feed speed of the grinding wheel head, as the grinding residual amount Δ, the maximum residual amount allowable value ΔMAX, and the workpiece W. As a function of the remaining grindable amount (remaining stock) up to the final diameter l, it is obtained from the following equation 4, and this value is RA
It is stored in the maximum allowable speed storage area 338 of M33. This value corresponds to the maximum value of the feed rate of the wheel head corresponding to the grinding state of the wheel. VMAX = f (Δ, ΔMAX, l) Equation 4 = S (ΔMAX + Δ ₂ −Δ) / n where Δ ₂ is the maximum allowable remaining amount ΔMA at the start of sparkout.
It is the current maximum allowable remaining amount for X, and is calculated using Equation 5. However, n = 1 / (ΔMAX / n) A = n / (1 + n) Then, the speed changing means 370 determines that the maximum allowable speed VMA
Compare X with the current feed rate of the grinding wheel head, and use line 374
The wheel head feed motor 63 is controlled via the to change the wheel head feed speed to the maximum allowable speed VMAX. Finally, the spark-out means 372 checks the final diameter of the workpiece W based on the input from the sizing device 40, and if the workpiece W has been ground to the maximum remaining amount allowable value ΔMAX, the line 37.
The wheel head feed motor 63 is controlled via 6 to stop the wheel head feed, and the spark-out time storage area 33 of the RAM 33 is controlled.
Spark out for the time T set to 6.

Next, the CPU of the numerical controller shown in FIG.
31 is a flowchart of FIGS. 5, 6 and 7, and FIG. 8 is a diagram showing an NC program for wheel head feed in this process.
Will be described in further detail in time series. In FIG. 8, the vertical axis indicates the wheel head position X, the horizontal axis indicates the time t, the solid line measures the workpiece diameter obtained from the wheel head position by the NC program of the wheel head feed, and the chain line measures by the sizing device 40. It represents the diameter of the workpiece. CP based on this NC program
U31 feeds the grindstone at a rough grinding feed (relatively high feed speed) until time a, and then performs a fine grinding feed (relatively slow feed speed) until the workpiece W is ground to the maximum remaining amount allowable value ΔMAX. And when the maximum remaining amount allowable value ΔMAX is ground, the feed is stopped and spark-out is performed for a preset time T.

In the flowchart of FIG. 5, first, rough grinding (corresponding to the time a from the start of feed of the wheel head in FIG. 8)
The process is performed from the following steps 501 to 504. First, the CPU 31 determines in step 501 that the RAM
The machining program stored in the NC data area 331 of 33 is read. Then, in the judgment step 502, it is judged whether or not this is a rough grinding feed command. When the command is not the rough grinding feed command (No in determination step 502), the process proceeds to step 503 to execute a process other than the rough grinding feed, for example, a process of starting rotation of a grindstone, injecting a grinding fluid, etc. The process returns to the reading process (step 501). If the command is a rough grinding command, rough grinding processing is performed (step 504). The rough grinding process in step 504 will be described with reference to FIG. First, the CPU 31 sends the grindstone head at the instructed feed speed (step 60).
1). Then, the process proceeds to the step of obtaining the remaining grinding amount Δ, which can correspond to the sizing measurement value input means 358, the wheel head position input means 354, and the remaining grinding amount calculation means 360 described with reference to FIG. First, the measured constant value RW is input (step 602), the wheel head position GP is input (step 603), and then the remaining grinding amount is calculated based on these values (step 604). This is the workpiece W
The radius dimension RW is added to the grindstone diameter RG stored in the grindstone diameter storage area 333 of the RAM 33, and the grindstone position GP is subtracted (calculation of the above-mentioned formula 1).

Next, it is determined whether or not the remaining grinding amount Δ is stable (decision step 605). This is the remaining grinding amount Δ
This is because the remaining amount coefficient, which will be described later, cannot be accurately obtained unless is stable. Specifically, the remaining grinding amount Δ is monitored in time series to determine the stability of the remaining amount. If the remaining grinding amount Δ is not stable, the process returns to step 602 for obtaining the remaining grinding amount, and the processing for calculating the remaining grinding amount is repeated. When the remaining grinding amount Δ is stable, the process proceeds to the remaining amount coefficient calculation process (step 606). The processing of the remaining coefficient calculation corresponds to the remaining coefficient calculation means 362 described with reference to FIG. 3, and here, based on the remaining grinding amount Δ and the feed speed stored in the feed speed setting area 332 of the RAM 33. The remaining amount coefficient η is calculated based on the above-described equation 2. Next, the routine proceeds to step 607 where the maximum remaining amount allowable value ΔMAX is calculated. This processing corresponds to the maximum remaining amount allowable value calculating means 368 in FIG. 3, and obtains the maximum remaining amount allowable value ΔMAX at the spark-out start time based on the above-mentioned equation 3. After the maximum remaining amount allowable value ΔMAX is obtained, the process proceeds to a determination step 608, and it is determined whether the grindstone head 61 has reached the rough grinding completion position a and the grindstone head feed has been completed. If the wheel head feed has not been completed, step 60 of sending the wheel head
Returning to step 1, when the feed of the grinding wheel head is completed, the rough grinding process (step 504 in FIG. 5) is completed, and the process proceeds to the next fine grinding process. This will be described with reference to FIG. 5 again.

Subsequent to the rough grinding, the fine grinding (corresponding to times a to b in FIG. 8) is performed in the following steps 505 to 508. First, the CPU 31 reads the machining program stored in the NC data area 331 of the RAM 33 in step 505. Then, it is judged in a judgment step 506 whether or not this is a fine grinding feed command. If the command is not the fine grinding feed command (determination step 506 is N
o), the process proceeds to step 507, the processes other than the fine grinding feed are executed, and the processing program is read (step 5).
Return to 05). If the command is the fine grinding command, the fine grinding process is executed (step 508). The fine grinding process in step 508 will be described with reference to FIG. First, the CPU 31 sends the grinding wheel head at the instructed feed speed (step 701). Then, the process proceeds to the step of obtaining the remaining grinding amount. First, the measured size RW is input (step 702), the wheel head position GP is input (step 703), and then the remaining grinding amount Δ is calculated based on these values.
Is calculated (step 704). This is performed by adding the grindstone diameter RG stored in advance in the grindstone diameter storage area 333 of the RAM 33 to the radius dimension RW of the workpiece W and subtracting the grindstone position GP input by the grindstone position input means 354 (Equation 1
Is calculated).

Next, the maximum permissible speed VMAX corresponding to the maximum permissible value of the feed speed of the wheel head is calculated based on the obtained remaining grinding amount Δ (step 705). This is shown in Figure 3.
Corresponding to the maximum permissible speed calculation means 364 of
Calculate using. Then, processing for speed adjustment, which corresponds to the speed changing unit 370 of FIG. 3, is performed below. First, it is judged whether or not the current feed speed of the wheel head is equal to the maximum allowable speed VMAX (decision step 706). When the current speed is equal to the maximum allowable speed VMAX (determination step 706 is Yes
In s), the speed is not changed and the process proceeds to the next judgment step 710. If the current speed is different from the maximum allowable speed VMAX, the process proceeds to the next judgment step 707. Decision step 70
At 7, it is determined whether the current speed is higher than the maximum allowable speed VMAX. When the current speed is higher than the maximum allowable speed VMAX, the feed speed of the wheel head is equal to or higher than the proper value, and the required grinding cannot be performed at this speed. Therefore, the determination step 707 becomes Yes, and the processing advances to step 708 to execute the deceleration processing for decreasing the speed. On the contrary, when the present speed is lower than the maximum allowable speed VMAX, the feed rate of the grinding wheel head is equal to or lower than the proper value, and the machine cycle of the grinding operation can be increased by further increasing the speed. Therefore, determination step 707 is No, and the process proceeds to step 709 to execute an acceleration process for increasing the speed.

Next, in a judgment step 710, it is judged whether or not the feed of the grinding wheel head is completed. This is performed by the grindstone base 61 in FIG. 8 detecting the precise grinding position b (position of the final diameter). Then, unless the feeding of the grinding wheel head is completed, the process returns to step 701, and by repeating the processing from step 701 to step 708, the grinding wheel head is always fed at the optimum speed. On the other hand, when the feed of the grindstone is completed, the fine grinding process (step 506 in FIG. 5) ends, and the process proceeds to the next spark out process. This processing will be described again with reference to FIG. Subsequent to the fine grinding, the spark-out (corresponding to time b after FIG. 8) processing is performed in the following steps 509 to 514. First, the CPU 31 reads a machining program in step 509. Then, it is judged in a judgment step 510 whether or not it is a spark-out command. If the command is not the spark-out command (No at the determination step 510), the process proceeds to step 511 to execute processing other than spark-out,
The processing returns to the processing program reading processing (step 509). When the command is the spark-out command, the process proceeds to step 512, the feed of the grinding wheel head is stopped, and the spark-out is started. Then, the spark-out is continued until the set time T, and when this time T has passed (Yes in the judgment step 513), the grinding wheel head is retracted (step 514), and all the processes are completed.

In the above-described embodiment, the feed rate of the wheel head is constant during the rough grinding process, and the feed rate of the wheel head is variable during the fine grinding process. It is of course possible to optimize the feed rate of the grinding wheel head by making the feed speed of the grinding wheel head variable by obtaining the speed. Further, in this embodiment, the maximum allowable speed calculating means 364 of FIG.
The maximum allowable remaining speed VMAX was calculated by using the calculated maximum allowable remaining value ΔMAX as one of the functions. Without using this, the maximum allowable remaining speed VMAX is calculated based on the remaining coefficient η and the final diameter l. VMAX can also be calculated directly. Also, in FIG.
In the process described with reference to FIG. 7, the remaining grinding amount was calculated in rough grinding (steps 602 to 604), and the remaining grinding amount was calculated again in fine grinding (step 702).
To step 704), it is possible to omit the processing from step 702 to step 704 by using the remaining grinding amount obtained in the rough grinding in the processing in this fine grinding. Further, in the above-mentioned embodiment, the spark out is started at the time when the feeding is completed in the machining program, that is, when the pulse distribution to the grinding wheel head 61 is completed, but the measured value of the sizing device 40 is the final diameter + the maximum remaining amount allowable value. Sparkout may be started when ΔMAX is reached.

As described above, in the grinding machine using the numerical control device of the present invention, the feed speed V of the grinding wheel base 61 is appropriately changed based on the size of the remaining grinding amount during the grinding process to improve the sharpness of the grinding wheel. Since it is set accordingly, stable grinding accuracy is obtained and the grinding processing time is shortened. Further, since the remaining amount of grinding ΔMAX for starting spark-out is also controlled based on the sharpness of the grindstone, the required grinding accuracy can be obtained by the preset spark-out time T, and
The cycle time can be shortened because the sparkout is not performed more than necessary. Also, since the maximum allowable remaining amount at the start of spark-out is managed, the time until the final diameter becomes constant even if the spark-out time is not constant. Even if the spark-out is completed at the time when it is detected, the same effect as in the above embodiment can be obtained.

[0023]

The present invention is configured as described above, and is controlled to be changed so that the feed speed of the grinding wheel head is appropriate based on the size of the remaining amount of grinding during the grinding process. As a result, a stable grinding accuracy is obtained by setting the feed speed according to the sharpness of the grindstone for the workpiece, and
This has the effect of shortening the grinding processing time. Further, the present invention is
Since the amount of grinding remaining to start spark-out is controlled based on the sharpness of the grindstone, the desired grinding accuracy can be obtained with a constant spark-out time and the spark-out is not performed more than necessary, so the cycle time is shortened. be able to. The present invention synergizes these effects, and has the effect of shortening the grinding processing time while maintaining the required processing accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall mechanical configuration of a numerically controlled grinding machine according to a specific embodiment of the present invention.

FIG. 2 is a block diaphragm showing an electrical configuration of a numerical controller and an operation panel according to the apparatus of the embodiment.

FIG. 3 is a block diaphragm showing an outline of functions of a CPU of the numerical controller according to the embodiment.

FIG. 4 is an explanatory view showing a relationship between a grindstone diameter and a sizing value at the time of grinding by the apparatus of the embodiment.

FIG. 5 is a flowchart showing a processing procedure of a CPU used in the apparatus of the embodiment.

6 is a flowchart showing a rough grinding processing procedure of the flowchart of FIG. 5;

FIG. 7 is a flowchart showing a processing procedure of fine grinding in the flowchart of FIG.

FIG. 8 is a view for explaining an NC program for wheel head feed, which is used to perform the processing of FIG.

FIG. 9 is a view for explaining an NC program for feeding a grinding wheel head in a conventional device.

FIG. 10 is a view for explaining a grinding process based on an NC program of a wheel head feed in a conventional device.

FIG. 11 is a diagram for explaining a grinding process based on an NC program of a wheel head feed in a conventional device.

[Explanation of symbols]

 20 Operation Panel 21 Operation Panel 22 Keyboard 23 CRT Display Device 30 Numerical Control Device 31 CPU 40 Sizing Device 50 Grinding Machine 51 Bed 52 Table 53 Table Feed Motor 59 Spindle Motor 60 Grinding Wheel 61 Grinding Wheel Drive 62 Grinding Wheel Driving Motor 63 Grinding Wheel Platform feed motor W Workpiece 354 Grindstone base position input means 358 Sizing measurement value input means 360 Grinding residual amount calculating means 362 Remaining amount coefficient calculating means 364 Maximum allowable speed calculating means 368 Maximum residual amount allowable value calculating means 370 Speed changing means 372 Spark-out means

Claims (1)

[Claims] 1. A numerical control grinder for processing a workpiece by moving a grinding wheel base on which a grindstone is supported by a workpiece at a predetermined feed speed, and a measuring device for measuring an outer diameter of the workpiece. And a grinding residual amount calculating means for calculating a grinding residual amount based on the outer diameter dimension of the workpiece measured by the measuring device and the grinding wheel position, based on the grinding residual amount and the feed speed of the grinding wheel platform. And a remaining amount coefficient calculating means for obtaining a remaining amount coefficient representing a grinding condition, and a maximum value for calculating an allowable value of the maximum remaining amount at the time of starting sparkout based on the remaining amount coefficient and a predetermined sparkout time. Remaining amount allowable value calculating means, speed changing means for changing the current feed speed based on the grinding remaining amount and the maximum remaining amount allowable value, and the fact that grinding has been performed up to the calculated maximum allowable remaining amount. Detects and sparks out A numerical control grinder equipped with a park-out means.