JP2000127038A - Sizing grinding control method for twin-head grinding machine and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sizing grinding control method for a twin-head grinding machine capable of grinding different work positions with two wheel spindle stocks simultaneously and independently and capable of concurrently completing the grinding and provide its device. SOLUTION: Different crankpins of a crankshaft can be ground simultaneously and independently by two wheel spindle stocks having follow-up sizing devices respectively in this sizing grinding control method for a twin-head grinding machine and its device. A work is concurrently measured (126) at least in one stage before the final grinding, e.g. after fine grinding (125), the cut quantity of the finish grinding for one revolution of the work is calculated (127) based on the measured result, the final grinding (128) is made according to the cut quantity, thus the grinding by two wheel spindle stocks can be concurrently completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-head crankpin fixed-size grinding control method and apparatus which can simultaneously and independently grind crankpins having different crankshafts by using two grinding wheels.

[0002]

2. Description of the Related Art A twin-head crankpin grinding method capable of simultaneously and independently grinding crankpins having different crankshafts by using two wheel heads is disclosed in Japanese Patent Laid-Open Publication No. Sho 54-7.
As already known from US Pat. No. 1,495,
Since the crank pin portion of the crankshaft, which is the machining portion, rotates around the journal portion of the crankshaft, when performing machining while directly measuring the machining portion, use a follow-up type sizing device to be described later. A method is employed in which the corresponding grinding wheel head is retracted based on a signal issued from the sizing device each time the portion reaches a predetermined size.

[0003]

However, in a twin head crankpin grinding or the like in which two different wheel heads can simultaneously and independently grind crankpins having different crankshafts, the processing by each wheel head is independent. In some cases, the grinding by each of the grinding wheel stands cannot be completed at the same time depending on the state of the workpiece, the state of the grinding wheel, and the like. In this case, the grindstone head which has completed the processing retreats quickly, and the resistance applied to the crankshaft changes, so that the crankshaft bends, which has a problem in that the roundness of the finished crankpin during the processing is affected. In addition, if one grindstone head is retracted during processing, there is a possibility that the sizing device or the like may interfere with other members.

Accordingly, an object of the present invention is to provide two grinding wheels in twin-head grinding in which two locations of the same workpiece, such as crankpins having different crankshafts, can be simultaneously and independently ground by two grinding wheels. It is an object of the present invention to provide a fixed-size grinding control method capable of performing safe and high-precision grinding processing by simultaneously completing the grinding processing, and an apparatus therefor.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a sizing grinding control method for a twin-head grinding machine according to the present invention comprises the steps of: This is a grinding control method for a twin-head grinding machine capable of simultaneously and independently performing grinding at different processing locations, and simultaneously performing measurement of a workpiece in at least one stage before final grinding. , The amount of grinding cut per one rotation of the workpiece in the next grinding process is calculated, and the grinding in the next step is performed based on the calculated amount of cut.

Further, according to the method of controlling sizing of a twin-head grinding machine of the present invention, a method for controlling sizing of a twin-head grinder is provided.
A grinding control method for a twin head crankpin grinding machine capable of simultaneously and independently grinding crankpins having different crankshafts simultaneously by two wheel heads, wherein at least one stage prior to final grinding processing, the workpiece is simultaneously ground. It is characterized in that the measurement is performed, the amount of grinding cut per rotation of the workpiece in the next grinding process is calculated based on the measurement result, and the next step is ground based on the calculated amount of cut.

[0007] In addition to the above features, the twin head grinding method according to the present invention further provides a method for controlling a fixed size grinding of a twin head grinding machine, wherein at least one step prior to final grinding is performed simultaneously. Measure the object,
It is characterized in that the number of times of calculating the grinding depth per one rotation of the workpiece in the next grinding process is set to a plurality of times based on the measurement result.

Further, the sizing grinding control apparatus for a twin head crankpin grinding machine according to the present invention simultaneously and independently and independently grinds crankpins having different crankshafts by using two grindstone tables each having a follow-up sizing apparatus. Means for indexing two wheel heads into processing positions, means for advancing two wheel heads for grinding, and two wheel heads prior to final grinding Means for simultaneously measuring the workpiece in at least one stage, means for calculating the amount of grinding cut per workpiece rotation in the next grinding process based on the measurement result, and grinding by the calculated amount of cut. Means for advancing the grindstone head in order to perform

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for controlling sizing of a twin-head grinding machine according to the present invention is a method for simultaneously and independently grinding different processing locations on the same workpiece by two grinding wheels each having a sizing device. A grinding control method for a twin-head grinding machine capable of performing machining, in which at least one stage before a final grinding process simultaneously measures a workpiece, and performs machining in a next grinding process based on the measurement result. Calculates the amount of grinding cut per one rotation of the workpiece, and performs the next process of grinding based on the amount of cut. Cylindrical grinding capable of simultaneously and independently performing grinding at different processing locations of the same workpiece at the same time. By applying to a crank pin grinder, etc., it is possible to perform high-precision grinding without biasing the load applied to the workpiece and to simultaneously retract two wheel heads. In which interference to other parts of the measuring device or the like is avoided.

In particular, according to the method of controlling sizing of a twin-head grinding machine of the present invention, a method of controlling sizing of a twin head grinder is provided.
By applying the present invention to a grinding control method for a twin head crankpin grinding machine capable of simultaneously and independently grinding crankpins having different crankshafts by using one grinding wheel head, the characteristic action and effect can be remarkable.

Further, according to the method of the present invention for controlling a fixed size grinding of a twin head grinding machine, in the method of controlling a fixed size grinding of the twin head grinding machine, the workpiece is measured simultaneously in at least one stage before final grinding. The number of times to calculate the grinding depth per one rotation of the workpiece in the next grinding process based on the measurement result is set to a plurality of times, for example, between rough grinding and fine grinding, and between fine grinding and final grinding. By performing the above two times, a more precise grinding operation can be performed by a fine sized grinding control method.

Further, the sizing grinding control apparatus for a twin head crankpin grinding machine according to the present invention is capable of simultaneously and independently grinding crankpins having different crankshafts by using two grinding wheels each having a follow-up sizing apparatus. Means for indexing two wheel heads into processing positions, means for advancing two wheel heads for grinding, and two wheel heads prior to final grinding Means for simultaneously measuring the workpiece in at least one stage, means for calculating the amount of grinding cut per workpiece rotation in the next grinding process based on the measurement result, and grinding by the calculated amount of cut. Means for advancing the grinding wheel head in order to perform With cutting machining can be performed, two grinding heads can be provided twin head crank pin grinder can avoid interference with other parts such as the sizing device by simultaneously retracted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. This is an embodiment in which the present invention is applied to a twin-head crankpin grinder. The twin-head crankpin grinder has two grinding heads 8, 9 as left and right working heads, as shown in FIG. A headstock 18 and a tailstock 17 that support the crankshaft W, which is a workpiece, are provided at positions that are slidable in the front-rear direction and are parallel to the grinding wheel axes of the grinding wheel stands 8 and 9. That is, on the bed 1, a right Z-axis table 6 on which a right wheel grind table 8 is mounted is slidably provided by a feed screw 3 on a Z-axis guide rail 2 in a longitudinal left-right direction (Z-axis direction). In the same row, a left-side Z-axis table 7 on which a left-side grindstone table 9 is placed in a longitudinal left-right direction (Z-axis direction) on the bed 1 is slidably provided by a feed screw 4. On each of the left and right Z-axis tables 6, 7, a grindstone table 8, 9 having a grindstone 14, 15 rotatably driven is provided in a longitudinal direction (X-axis direction) orthogonal to the longitudinal left-right direction (Z-axis direction). It is slidably provided by the respective feed screws 12 and 13.

A headstock 18 and a tailstock 17 are provided in the front longitudinal direction of the left and right wheel heads 8 and 9, and a crankshaft W as a workpiece is supported by a pair of centers therebetween. . The headstock 18 is provided with a servomotor 18M for driving the rotation of the crankshaft. The headstock 18 is configured so that the shaft end of the crankshaft W can be gripped by a chuck or the like and can be driven to rotate. It is configured to support the axis of W.

Each of the feed screws is provided with a servomotor with an encoder, and is controlled by a control device described later. That is, a servomotor 60 with an encoder 70 is provided at an end of the feed screw 3 for moving the right Z-axis table 6 on which the right wheel grind table 8 is placed in the left-right direction (Z-axis direction). The feed screw 4 for the shaft table 7 is provided with a servomotor 68 with an encoder 72. Also, the left and right Z-axis tables 6,
Servomotors 44 and 48 with encoders 50 and 52 are provided on the end 7 of feed screws 12 and 13 for sliding in the front-rear direction (X-axis direction) of the grindstone heads 8 and 9. The grindstones 8 and 9 support the grindstones 14 and 15 so as to be driven to rotate. Naturally, a driving motor for driving the grindstones is driven by the grindstones 8 and 9.
9 is built in.

The schematic configuration of the twin-head crankpin grinder according to the embodiment of the present invention is as described above.
A crankshaft W which is a workpiece is supported between the headstock 18 and the tailstock 17, and the left and right Z-axis tables 6 and 7 are processed by the servomotors 60 and 68 so that the grindstones 14 and 15 are processed by the crankshaft W. In FIG. It is indexed to a position aligned with the crankpins CP (a) and CP (c). Next, the spindle drive servomotor 18M with the encoder 18E of the headstock 18 is rotated to control-rotate the crankshaft W. At this time, since the crankshaft W is rotated about the axis of the bearing portion, the crankpins CP (i) to CP
(C) makes a turning motion. Then, the X-axis direction feed screws 12, 13 on both the left and right tables 6, 7 are moved forward and backward by the respective servo motors 44, 48. that time,
Since the crank pins CP (a) and (c), which are the processing portions, are turning, the main shaft servo motor 18M is controlled by the control means.
Grinding is performed by the rotating grindstones 14 and 15 while the grindstone stands 8 and 9 are moved back and forth in synchronization with the rotation of. In accordance with the grinding operation, the servomotors 44 and 48 of the grinding wheel heads 8 and 9 give a cutting forward movement, and operate so as to gradually finish to the final finishing dimensions.

The twin head crankpin grinding machine according to the embodiment of the present invention has a sizing device 20 as shown in FIG.
Is placed. The sizing device 20 is a well-known following sizing device (for example, manufactured by Marposs, Italy) of the type that measures the dimensions of a processing portion while constantly contacting the rotating crank pin while following the same. 2 will be described. The support member 21 of the sizing device 20 is provided on the upper surface of the grindstone table 9.
Is mounted, a second arm 23 is pivotally supported at a tip of a first arm 22 pivotally supported by the support member 21 and extending forward of the grindstone 15, and a measurement for measuring at a right angle to the tip of the second arm 23. A rod 28 is fixed. The measuring rod 28 includes a V-block 25 fixed to the tip thereof and in contact with the outer periphery of a crank pin CP (c) as a processing portion, and a probe 27 provided at the center thereof so as to be able to advance and retreat.
Is electrically detected and output as an electric signal. A guide member 26 is fixed to the tip of the V block 25, and the V block 2 of the measuring rod 28 is fixed.
Reference numeral 5 serves as a guide for engaging the crankpin CP (c). The sizing device 20 is provided with an operating device for moving the measuring rod 28 between a rest position (a two-dot chain line position) and a measurement position (a solid line position). A hydraulic cylinder 31 is provided on the upper surface of the grindstone table 9, and the first arm 22
The first arm 22 is rotated upward by pressing the operating piece 30 attached to the rear end of the cylinder vertically and offset by the piston 32 of the cylinder 31, and FIG.
At the rest position shown by the two-dot chain line. At this time the second
Since the arm 23 is only pivotally supported by the tip of the first arm 22 and cannot maintain its position, the third arm 24 is fixed below the tip of the first arm 22, and the tip of the tip of the third arm 24 is fixed. The support arm 29 is configured to maintain the position of the second arm 23. From the rest position of the two-dot chain line,
When the measuring rod 28 gradually descends by returning the piston 32 of the hydraulic cylinder 31 to the position of the crankpin CP (c), the guide member 26 first moves the crankpin CP (c).
And the crank pin CP along the guide member 26
(C) engages with the V block 25,
At that time, the second arm 23 is separated from the support protrusion 29 of the third arm 24 and can freely rotate.

Next, a control device for a twin-head crankpin grinding machine according to an embodiment of the present invention will be described. As shown in FIG. 3, the present control system includes a numerical controller 78. The numerical controller 78 includes a CPU 80 for controlling the right side grinding wheel and a CPU 90 for controlling the left side grinding wheel, the ROMI09, and the RAM 111 via the bus 88. It is configured to be connectable to. An X-axis servo motor control circuit 84 and a Z-axis servo motor control circuit 86 are connected to the right wheel control CPU 80 via an interface 82. The right X-axis servo motor 44 is connected to the X-axis servo motor control circuit 84, and the encoder 50 is disposed on the right X-axis servo motor 44 as described above.
Are connected to the control circuit 84 for the X-axis servo motor. The right Z-axis servo motor 60 is connected to the Z-axis servo motor control circuit 86, and the encoder 70 described above is disposed in the right Z-axis servo motor.
0 is connected to the control circuit 86 for the Z-axis servo motor.

An X-axis servo motor control circuit 94, a Z-axis servo motor control circuit 96, and a main spindle servo motor control circuit 98 are connected to the left wheel control CPU 90 via an interface 92. The control circuit 94 for the X-axis servo motor includes the left X-axis servo motor 48
The energizer 52 is disposed on the left X-axis servo motor 48, and the encoder 52 is connected to a control circuit 94 for the X-axis servo motor. The control circuit 96 for the Z-axis servo motor includes a left Z-axis servo motor 68
Is connected to the left Z-axis servomotor.
The encoder 72 is connected to a control circuit 96 for a Z-axis servomotor. A spindle servo motor 18M is disposed in the spindle servo motor control circuit 98, and the spindle servo motor 18M has an encoder 18M.
The encoder E is connected to the spindle servomotor control circuit 98. The bus 88 is connected to the CRT 1 via the interface 101.
And an input / output device 107 including a numeric keypad 105 and a numeric keypad 105 are connected. The ROM 109 stores a system control program and the like, and the RAM 111 stores a machining program and the like. Further, in addition to the numerical controller 78, a sequence controller 112 is connected to the bus 88 via an interface 113, and left and right sizing devices 20L and 20R provided on both the left and right grinding wheel heads are provided with A-D.
It is connected via an interface 114 containing a converter.

Next, a specific control method which is a feature of the present invention will be described with reference to the flowchart of FIG. 4 showing the control steps. First, in accordance with a signal of the processing start 120, indexing is performed to align the left and right grinding wheel heads 8 and 9 with the crank pins CP (a) and CP (c) at the processing position, respectively (121). Next, both wheel heads are moved forward (122)
And insert the sizing device into the crank pin (12
3). From the stage where the grindstone comes into contact with the processed part of the crankpin, the two grindstones advance to the coarse grinding advance (124), and from the stage of grinding a certain amount to the fine grinding advance (125). Therefore, the feed of the grinding wheel head is stopped and zero-cut grinding (126), that is, the dimension value measurement (126) is performed by a sizing device while performing spark-out, and based on the measurement result, the final grinding is performed based on the difference from the finished dimension. The number of cuts per work in the final grinding process is calculated by gradually calculating the number of rotations of the work and determining the number of rotations to finish the work. (127), and the final grinding advance (128)
I do. Zero cut grinding (spark out) again (12
9) is performed to complete the grinding of the crankpins CP (a) and CP (c), the sizing device is returned to the rest position, and the grindstone head is retracted (130).

The above-mentioned grinding cycle is illustrated in FIG. 5, and conceptually from the stage (a) in which the sizing device is inserted from the rapid traverse advance and the grinding wheel comes into contact with the processing portion as indicated by the upper line. Coarse grinding feed is advanced for about 8 rotations of the crankpin. From the stage of grinding a certain amount (b), the crankpin is ground for about 5 rotations by fine grinding feed advance (c). The dimension value is measured by the sizing device while performing (spark-out) for one to two rotations, and based on the measurement result, the cut amount per work rotation in the final grinding process is calculated (127), and the final value is calculated based on the value. The grinding advance is performed about 3 to 5 rotations (e), zero-cut grinding (spark-out) is performed for one rotation, and the grinding of that part is completed (f), and the grinding wheel head is retracted.

In the case of the present invention, a separate crank pin CP is provided by the two right and left grinding wheel heads 8 and 9 which are individually controlled.
(A) and CP (c) are simultaneously ground, and the degree of processing progress is different. Therefore, the diameter dimension of each of the crankpins CP (a) and CP (c) follows a locus as shown by the lower line in FIG. The diameter before grinding of the crank pin as the workpiece is Db and the finished diameter is Df, and the difference is a margin. Although the first rough grinding and the subsequent fine grinding are performed, the grinding with the two wheel heads is not exactly the same. Therefore, in the dimension value measurement at the time of zero incision grinding (spark out), the difference from the finished dimension, that is, the final allowance There is a difference between Δd1 and Δd2. Therefore, as a feature of the present invention, the number of rotations n of the crankpin in the final grinding and finishing is determined (usually about 3 to 5 rotations), and the allowances Δd1 and Δd2 in the final grinding are gradually reduced so that the number of rotations per crankpin is reduced. Cutting amount Δd1 /
By calculating n and Δd2 / n and performing the final grinding at the respective cutting depths, the finishing dimensions of the two wheel heads can be completed simultaneously when the crankpin is rotated n times. Thereafter, zero-cut grinding (spark-out) is performed about once, the grinding process of the portions CP (a) and CP (c) is completed, the sizing device is returned to the rest position, and the grindstone table is simultaneously retracted.

Therefore, a highly accurate grinding process can be performed without biasing the load applied to the crankshaft at the time of grinding by the two wheel heads, and the other parts of the sizing device can be simultaneously moved by the two wheel heads retracting simultaneously. Interference is avoided. In addition, FIG. ] To step (131), in which case the crankpin C
Since the grinding of P (b) and CP (d) remains, (N
o), the process returns to the first step again, and the grindstones 8 and 9 are indexed to positions where both grindstones are aligned with the crankpins CP (b) and CP (d) (121), and the same grinding cycle is executed. When the grinding of all the crankpins is completed, both grinding wheels are returned to the original positions at the left and right ends (132), and all the grinding cycles are completed (133).

Next, a modification of the sizing grinding control method according to the present invention will be described with reference to FIG. The outline is the same as that of FIG. 4 described above. First, the left and right grindstone heads are moved by the signal of the processing start (140), and the crank pin
(A), indexing is performed to align with CP (C) (141). Next, the two grinding wheels 8 and 9 are advanced in rapid traverse (1).
42) Insert the sizing device into the crank pin (1)
43). From the stage where the grindstone comes into contact with the processed part of the crankpin, the two grindstone heads advance to the coarse grinding advance (144), and measure the dimensions at the stage of grinding a certain amount. The cutting amount per rotation is calculated (145), and the fine grinding feed is advanced based on the calculation result (146). When the fine grinding is completed, the dimension is measured by the sizing device, the difference from the finished dimension is calculated based on the measurement result, and the cut amount per rotation of the work in the final grinding is calculated (147).
The final grinding advance is performed according to the value (148). After the final grinding is completed, zero-cut grinding (spark-out) is performed (149).
Is finished, the sizing device is returned to the rest position, and the grinding wheel head is retracted (150). Subsequent operations are the same as those in FIG. Since the cutting feed amounts of the two right and left wheel heads 8 and 9 are adjusted based on the results of the two dimensional measurements and the end times of the grinding operations are matched, the grinding resistance applied to the crankpin becomes uniform. , More accurate grinding can be performed. Steps (145) and (147)
Is performed in the spark-out state after the cuts in the previous steps (144) and (146) are completed.

(Other Embodiments) The above embodiment is applied to a twin head crankpin grinder.
The grinding control method of the present invention is not limited to crank pin grinding,
The present invention is applicable as long as it can simultaneously process two processing portions of the same workpiece, and can be applied to, for example, a cylindrical grinder capable of performing plunge cutting.

[0026]

According to the present invention, there is provided a grinding control for a twin-head grinding machine capable of simultaneously and independently performing grinding on different processing portions of the same workpiece simultaneously by two grinding wheels each having a sizing device. A method for simultaneously measuring a workpiece in at least one stage prior to finish grinding, calculating a cutting amount of finish grinding per one rotation of the workpiece based on the measurement result, and performing finishing by the cutting amount. Since the grinding is performed, the end time of the grinding operation of the two grinding heads can be matched, and the grinding resistance applied to the workpiece becomes uniform, so that there is no risk of adversely affecting roundness and the like, and high precision is achieved. Grinding can be performed.

Further, by applying the method for controlling the fixed size grinding of the twin head grinding machine of the present invention to a crankpin grinding machine, the end times of the grinding processes of the two crankpins can be matched, and the grinding applied to the crankshaft can be performed. Since the resistance becomes uniform, there is no possibility of adversely affecting the roundness of the crankpin, etc., and high-precision grinding can be performed. In addition, since the two grinding wheels are retracted simultaneously, a sizing device, etc. Will not interfere with other parts.

Further, in the method for controlling the size of a twin-head grinding machine according to the present invention, the workpiece is measured simultaneously, and the number of times of calculating the cutting depth per one rotation of the workpiece is calculated based on the measurement result. By setting the number of times, grinding with higher precision can be performed.

[Brief description of the drawings]

FIG. 1 is a plan view of a twin head crankpin grinding machine of the present invention.

FIG. 2 is a side view showing a sizing device in the twin head crankpin grinding machine of the present invention.

FIG. 3 is a block diagram showing a fixed-size grinding control device for a twin-head crankpin grinding machine according to the present invention.

FIG. 4 is a control flowchart of fixed-size grinding control of the twin-head crankpin grinding machine of the present invention.

FIG. 5 is a grinding cycle diagram of fixed size grinding control of the twin head crankpin grinding machine of the present invention.

FIG. 6 is another control flowchart of fixed-size grinding control of the twin-head crankpin grinding machine of the present invention.

[Explanation of symbols]

 1: Bed 8: Right wheelhead 9: Left wheelhead 14: Right wheel 15: Left wheel 17: Tailstock 18: Headstock 22: Sizing device 28: Measuring rod 27: Probe 78: Numerical controller

Continued on the front page (72) Inventor Chisen Kato 1-1-1, Asahi-cho, Kariya-shi, Aichi Toyota Machine Works Co., Ltd. (72) Inventor Toshihiro Yonezu 1-1-1, Asahi-cho, Kariya-shi, Aichi Prefecture F term (reference) 3C034 AA01 AA13 AA19 CA02 CB01 DD20 3C043 AC25 CC03 CC11 DD06

Claims (4)

[Claims] 1. A grinding control method for a twin-head grinding machine capable of simultaneously and independently performing different grinding operations on different processing portions of the same workpiece by two grinding wheels each having a sizing device. In at least one stage before the final grinding, the workpiece is measured at the same time, and based on the measurement result, a grinding depth per one rotation of the workpiece in the next grinding process is calculated, and the next depth is calculated based on the depth. A fixed-size grinding control method for a twin-head grinding machine, wherein the grinding is performed in a process. 2. A grinding control method for a twin head crankpin grinding machine capable of simultaneously and independently grinding crankpins having different crankshafts respectively by two grinding wheels each provided with a tracking type sizing device. In at least one stage before the final grinding, the workpiece is measured at the same time, and based on the measurement result, a grinding depth per one rotation of the workpiece in the next grinding process is calculated, and the next depth is calculated based on the depth. A fixed-size grinding control method for a twin-head crankpin grinding machine, characterized by performing a grinding process. 3. The method according to claim 1, wherein the measurement of the workpiece is performed simultaneously in at least one stage before the final grinding, and the workpiece is measured in the next grinding step based on the measurement result. 3. The method according to claim 1, wherein the number of times of calculating the grinding depth per rotation is a plurality of times. 4. A twin-head crankpin grinding machine capable of simultaneously and independently grinding crankpins having different crankshafts by using two wheel heads each provided with a tracking type sizing device. Means for indexing to the machining position, means for advancing the two wheel heads for grinding, means for simultaneously measuring the workpiece in the two wheel heads in at least one stage before the final grinding, and the measurement thereof Means for calculating the amount of grinding cut per rotation of the workpiece in the next grinding step based on the result;
Means for advancing the grinding wheel head to perform grinding with the calculated cutting depth. A fixed-size grinding control device for a twin-head crankpin grinding machine.