JPH05138513A - Cylinder grinder equipped with wheel spindle stocks facing each other - Google Patents

Abstract

PURPOSE:To enhance the grinding precision even if a work is a lengthy one and improve the grinding efficiency by minimizing the need of swing stop by providing at a machine stock two wheel spindle stocks which face each other and are advanceable/retreatable toward both sides of almost the same position in the axial direction of the work supported by means of a main shaft stock and a tail stock. CONSTITUTION:Wheel spindle stocks 16, 116 which face each other and are advanceable/retreatable toward both sides of almost the same position in the axial direction of a work W supported by means of a work main shaft stock 6 and a tail stock 7, are equipped at a machine stock 1. As a result, guides 17, 117 are provided at the machine stock so as to meet at right angles with a guide 2 to guide a table 3, and respective wheel spindle stock main bodies 18, 118 are slidingly joined to guides 17, 117. Grinding wheel spindles 19, 119 that are respectively in parallel with the work W are supported rotatably at wheel spindle stocks 18, 118. Grinding wheels 23, 123 fitted to these grinding wheel spindles 19, 119 are located on sides opposite to each other with the diameter of the work W interposed, and at the same position in the axial direction of the work W. As a result, grinding precision can be increased by making a bending moment small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical grinder and a cylindrical grinder suitable for grinding a long cylindrical workpiece.

[0002]

2. Description of the Related Art Conventionally, a long cylindrical workpiece has a low rigidity, and when it is ground by a cylindrical grinder, vibration occurs, the workpiece is elastically deformed and the roundness is not good, or the cylindricity is low. It is easy to be unable to secure it. When grinding such a non-rigid work piece, a sway stopper is generally used.

[0003]

Since the work piece whose length is remarkably larger than the diameter is not rigid, it opposes the grinding force, and therefore the shoe is applied to the outer diameter portion of the work piece. Since the cutting of the grindstone into the work piece is performed several times until the required diameter is reached, the anti-sway shoe needs to be fed toward the work piece, and the position of the anti-sway shoe must be adjusted. Since the number of such sway stoppers increases and the workpieces are supported as the length of the workpieces increases, it takes time to adjust the sway stoppers during processing. If this point is described in more detail, the grinding force that is a combination of the main component force of the grinding resistance and the back force component is applied to the workpiece. A two-point anti-sway with a shoe that receives this main force and a shoe that receives it by the back force is generally used. In this case, the shoe that receives the back force directly affects the grinding accuracy and must be sent to a predetermined position with respect to the workpiece. Further, since a large force is applied to the shoe that receives the main component force, it can be placed in the retracted position by taking account of the wear resistance and utilizing the elasticity of the workpiece to some extent. Therefore, when adjusting the anti-sway, the shoes that receive the back force may simply and independently be located at the same position with respect to the workpiece diameter, but the shoes that receive the main force should be processed by each anti-sway arranged in the axial direction. It is necessary to adjust the feed amount to the work piece according to the manner of supporting the work piece. As mentioned above, it takes time to adjust the anti-sway. Therefore, the number of sway stoppers is kept to the minimum necessary and the cutting amount of the grindstone is limited.

Since the grinding method as described above is performed, the depth of cut is small, and the adjustment of the runout requires a considerable processing time. It is very difficult to improve the grinding accuracy because it is necessary to adjust two shoes in different directions with respect to one anti-vibration tool and the shoe positions of each anti-vibration tool are related to each other.

The present invention has been made in view of the above points, and an object of the present invention is to provide a cylindrical grinding machine which can improve the grinding accuracy, can reduce the number of sway stoppers, and have a good grinding efficiency.

[0006]

A first aspect of the present invention is a machine base, a table reciprocally movable on the machine base, a table drive device, and a workpiece provided on the table so as to face each other. A headstock and a tailstock, and two opposing grindstones provided on the machine base so as to be capable of advancing and retracting toward and away from the workpiece on both sides at substantially the same axial position of the workpiece supported by the headstock and tailstock. , A cylindrical grinder provided with an opposed grindstone head and a whetstone head driving device.

A second aspect of the present invention is provided with a grindstone correcting device which acts on the grindstone in the retracted position of the grindstone base, and the grindstone correcting tool is arranged at a position opposite to the position where each grindstone acts on the workpiece. A cylindrical grinding machine provided with the facing grindstone base according to the first aspect of the invention.

According to a third aspect of the present invention, a whetstone head driving device has a single feed screw arranged in the whetstone head cutting direction,
The feed screw is provided with screw portions having different twist directions,
The nuts screwed into the threaded portions are attached to the respective grindstone bases, and the cylindrical grinder is provided with the facing grindstone base according to the first invention or the second invention.

A fourth aspect of the present invention is characterized in that at least one of the nuts attached to each whetstone is fixed by rotation so that the position in the rotational direction can be adjusted. It is a cylindrical grinder equipped with the facing grindstone.

In a fifth aspect of the present invention, each grindstone head has a driving device, and each driving device connects the grindstone head to a servomotor controlled by one numerical controller via a screw feeder. The first invention or the second invention characterized in that
Is a cylindrical grinder provided with the facing grindstone.

According to a sixth aspect of the present invention, each grindstone is mounted on each saddle so as to move back and forth toward the workpiece, and each saddle is fixed to the guide of the machine base parallel to the table so that its position can be adjusted. It is a cylindrical grinding machine provided with the facing grindstone stand according to the fifth aspect of the invention.

According to a seventh aspect of the present invention, there is provided the opposed grindstone head according to any one of the first to sixth inventions, wherein the grindstones of both grindstone heads rotate in the same direction. It is a equipped cylindrical grinder.

An eighth invention of the present invention is characterized in that the grindstone rotating directions of both grindstones are opposite to each other, and the facing grindstone according to any one of the first to sixth inventions. It is a cylindrical grinder equipped with.

A ninth invention of the present invention is characterized in that at least one of the main electric motors for driving the grindstones provided on the grindstone mounts of the two grindstone mounts is capable of forward and reverse rotation. It is a cylindrical grinder provided with the opposite grindstone stand described in any one of the above.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a plan view, FIG. 2 is a front view of FIG. 1, and FIG. 3 is a side view of FIG. 1 showing a partial cross section.

A so-called V-hira guide 2 provided on the machine base 1.
The table 3 is slidably attached to the table 3, and the table 3 can reciprocate on the machine base 1. The drive device 4 of the table 3 is a hydraulic cylinder 5 whose cylinder case is fixed to the machine base 1 and whose piston rod is fixed to the table 3, and an attached hydraulic device. A workpiece headstock 6 is fixed on the table 3 in the direction in which the table 3 reciprocates, and a tailstock 7 is fixed so as to face the workpiece headstock 6 so that its position can be adjusted. The work headstock 6 is input from an upper electric motor 10 via a belt device 8, and the rotation is transmitted to a work main shaft 9 via an internal reduction gear. The workpiece W is supported by a center 11 that is fitted into the workpiece spindle 9 and a center 13 that is fitted into a sleeve 12 that is adjusted in and out of the tailstock 7. Workpiece W is a wrench 14 fixed to the workpiece W.
It is rotated by the driving tool 15 engaged with. The driving tool 15 is fixed to the workpiece spindle 9.

The machine base 1 is provided with grindstone mounts 16 and 116 which are opposed to each other at substantially the same position in the axial direction of the workpiece W supported by the workpiece headstock 6 and the tailstock 7 so as to be movable back and forth. ..
Therefore, a guide 2 for guiding the table 3 is provided on the machine base 1.
The guides 17 and 117 are provided so as to be orthogonal to, and the respective whetstone base bodies 18 and 118 are slidably engaged with the guides 17 and 117. Grindstone shafts 19 and 119 parallel to the workpiece W are rotatably supported on the grindstone bases 18 and 118, respectively. Main motors 21 and 121 provided on the grinding wheel base bodies 18 and 118 and the grinding wheel shafts 19 and 119 are connected by belt devices 22 and 122. The grindstone shaft 19, 119 has a cylindrical grindstone 23,
123 is attached. The grindstones 23 and 123 are on opposite sides of the diameter of the workpiece W, and are at the same position in the axial direction of the workpiece W. However, the grindstones 23 and 123 may be displaced in the axial direction of the workpiece W. If the workpiece is constant and the grinding conditions are constant, the grindstone 2
Since the amount of displacement of 3,123 may be constant, the guide 17,
117 is provided on the machine base 1. In order to make the amount of displacement variable, guides parallel to the table 3 are provided on the machine base 1 on both sides of the table 3, and saddles are slid on the respective guides so that the positions of the saddles can be adjusted. A fixing device for the saddle is provided, and the same guides as the guides 17, 117 are provided on the saddle to mount the respective grindstones 16, 116. A drive device for the grinding wheel heads 16, 116 is provided in the saddle, and in this case, the grinding wheel heads 16, 11 are driven.
The driving device 6 is the one shown in FIGS. 7 and 8 described later, that is, a servo motor, a screw feed device, and a numerical control device (not shown).

On such a saddle, the grindstones 16, 116 are mounted.
In addition to shifting the positions of the grindstones 23 and 123 in the axial direction, the grindstones 23 and 123 are set to the same position in the axial direction, and when grinding a part far away in the axial direction of the workpiece, By moving 16 and 116 in the axial direction, the stroke of the table 3 can be reduced and each portion to be ground can be ground.

The machine base 1 is provided with a drive device for the grindstone bases 16 and 116.

Next, a drive device for the grinding wheel heads 16 and 116 will be described. As shown in FIG. 3, a feed screw 24 parallel to the guides 17 and 117 for guiding the grindstone bases 16 and 116 is supported below the grindstone mounts 16 and 116 by a bearing 25 so as not to move in the axial direction on the machine base 1. ing.

The feed screw 24 is a threaded portion 2 which is opposite to each other.
6,126 are provided. A nut 27 is screwed into the screw portion 26, and a nut 127 is screwed into the screw portion 126. The nut 27 is rotatably supported by a bearing 29 in a nut case 28 fixed to the grindstone base 16 so as not to move in the axial direction. A second-stage worm wheel 31 is fixed to the nut 27, and the second-stage worm wheel 31 meshes with a second-stage worm 32 supported by the machine base 1 and is integrated with the second-stage worm 32 to form a first-stage worm wheel. The first stage worm 34 is engaged with 33. 1
Both grindstone position adjusting shafts 35 to which the step worms 34 are fixed are rotatably supported by the nut case 28 via bearings 40 so as not to move in the axial direction. The adjusting shaft 35 is the shaft 4
0a is spline-coupled, the shaft 40a is supported by the machine base 1 via a bearing 40b so as not to move in the axial direction, protrudes to the outside in front of the machine base 1, and both grindstone position adjusting handles with a micrometer collar are attached to the shaft end. 36 is attached.
An automatic cutting device 37 that drives the feed screw 24 each time the table 3 reciprocates is connected to the feed screw 24, and the feed screw 24 is connected to a cut handle 39 via a micrometer device 38. The automatic cutting device 37 and the micrometer device 38 are well known in the field of cylindrical grinders, and therefore their explanations are omitted. The fixing screw 41 for the feed screw 24, which is screwed into the machine base 1, fixes or releases the feed screw 24 directly or at a portion of the feed screw 24 which is rotated at an increased speed.
A lever 42 is provided.

Grinding wheel correction devices 43 and 143 are provided on the machine base 1. The grindstone correcting devices 43 and 143 face the grindstone correcting tools 44 and 144, respectively, and
It acts on the grindstones 23, 123 from the back of the above, and since it has the same configuration, the grindstone correcting device 43 will be described. The grindstone correction tool 44 is a single stone diamond or a rotary dresser, and in this example, the case of a single stone diamond will be described for simplicity of explanation. Whetstone correction tool 44
Is attachable to and detachable from the grindstone correction tool base 45.

The grindstone correcting tool 44 is the center of the work spindle 9 of the work headstock 6, that is, the center 11 and the center 1 of the tailstock 7.
It is guided by the machine base 1 so as to be slidable in the direction of (a) in parallel with the center line connecting the three, and is connected to the correction grindstone drive device 46 which reciprocates in the direction of the arrow (a) shown.

Next, the operation of the above configuration will be described. The cuts in the work W are shown in FIG. 4 as an example. The blank diameter D0 of the workpiece W is usually turned and hardened. When the cutting amount of the grindstone 23 per time is t1 and the cutting amount of the grindstone 123 is t2, the workpiece diameter D1 = D0- (t1 + t2) when the table 3 is moved by one cut. As for the rotation direction, when the workpiece W is clockwise in FIG. 4, the normal grindstones 23 and 123 are clockwise, and the moving direction of the peripheral surface of the workpiece W and the peripheral surface moving directions of the grindstones 23 and 123 are opposite directions. .. When the anti-sway is not used, the cuts t1 and t2 are selected so that the main components of the grinding resistance of the grindstones 23 and 123 are almost equal.

In order to initialize the cutting conditions for grinding as described above, the lever 42 is turned to tighten the feed screw fixing screw 41, the feed screw 24 is made immobile, and the grindstone positional relationship adjusting handle 36 is rotated. , Both grindstone position adjusting shafts 35 rotate, and the first stage worm 34 rotates. The first stage worm 34 rotates the first stage worm wheel 33,
The step worm 32 rotates integrally. Since the second stage worm 32 rotates the second stage worm wheel 31, the nut 27 is supported by the bearing 29 and rotates, and the whetstone head 16 moves. As a result, the whetstone base 16 is first retracted more than the whetstone base 116.

A master having a diameter D1 with an accurate cylindrical surface formed on the outer circumference is attached between the headstock center 11 and the headstock center 13, and the feed screw 24 is rotated by returning the lever 42 for fixing the feed screw for notch, and making the notch. The feed handle 39 is rotated to bring the grindstone bases 16 and 116 closer to each other. Then, the grindstone 123 is brought into contact with the master, the feed screw fixing lever 42 is rotated again to fix the feed screw 24, and the grindstone positional relationship adjusting handles 36 are rotated to rotate the grindstone 16
To move the grindstone 23 into contact with the master. Next, the handle 36 is rotated in the opposite direction to the scale opposite to the above, and the horizontal distance between the facing surfaces of the grindstone 16 and the workpiece W is set to the grindstones 23, 12.
The grinding wheel base 16 is retracted so that the cutting depth difference of 3 is t2, and the cutting feed screw fixing lever 42 is loosened.

Next, the master is removed from the headstock center 11 and tailstock center 13, the turning bar 14 is attached to the blank of the workpiece W, the center 11 of the workpiece headstock 6 and the tailstock 7 are attached.
The workpiece W is attached between the centers 13 of the above, and the driving tool 15 and the turning bar 14 are engaged. When the electric motors 10, 21, 121 are rotated, the workpiece main shaft 9 and the grindstone shafts 19, 119 rotate via the belt devices 8, 22, 122, respectively, and the workpiece W and the grindstones 23, 123 rotate. The table 3 is moved so that the grindstones 23 and 123 come to the tail end side end positions of the workpiece W, the cutting handle 39 is rotated to rotate the feed screw 24, and the grindstone bases 16 and 116 are brought close to each other. When the grindstone 23 is cut so that the cut becomes t1, the cut amount is set as shown in FIG. That is, the cutting of the grindstone 23 is t1,
The cut of the grindstone 123 is t2. On the other hand, before this, the required cutting amount is set in the automatic cutting device 37. Here, when the table driving device 4 is driven to reciprocate the table 3, the workpiece W is ground.

As shown in FIG. 4, the grinding resistance applied to the workpiece W is as follows: the grinding resistance of the grindstone 23 is the main component force F1, the back force component F2, and the grinding resistance of the grindstone 123 is the main component force F101, the back component force 102. , The main component force F1≈F101, and the back component force F2≈F102. However, the relationship between the rotation speed of the workpiece W and the feed speed of the table 3 is important. That is, the pitch of the spiral showing the working position of the grindstones 23, 123 drawn on the workpiece W is the grindstone 2
It is determined in consideration of the width of 3,123.

As described above, since the grinding resistances of the grindstones 23 and 123 can be balanced, little bending force is applied to the workpiece W, so that even if the workpiece W is long and slender, it can be machined without swaying. Even in the case, the number is extremely small compared to the conventional case. The sway stopper may be a V block 48 that moves up and down from below as shown in FIG. 5, or a catch 49 that moves up and down from below as shown in FIG. 6 and has a flat upper surface. The outer periphery of the workpiece is ground by such sway stopper,
Even if the outer diameter of the work piece becomes thin and there is a gap between the outer circumference of the work piece and the top of the anti-slip, and the work piece bends due to grinding resistance during grinding, the work piece is displaced in the grinding direction of the grindstone. It has almost no effect on the grinding accuracy of the object.

The grindstones are corrected by the grindstone correcting devices 43 and 143 by retracting the grindstone bases 16 and 116.

Next, another embodiment will be described. FIG. 7 shows a side sectional view corresponding to FIG. 3 of the previous embodiment.
FIG. 8 is a plan view of FIGS. 8 and 7. In this embodiment, the cutting feed is carried out by a numerical control device, which is different from the previous embodiment. That is, the numerical controller 51 uses the servo motor 5
2, 152 are numerically controlled, each servo motor 52, 152 is connected to a ball screw 53, and a ball nut 54 screwed into the ball screw 53 is a wheel head 1.
It is fixed to 6,116. The origin positions of the grindstone bases 16 and 116 are determined, and the working positions of the grindstones 23 and 123 are corrected by the grindstone correction cutting amounts of the grindstone correction devices 43 and 143, and the grindstones 23 and 12 are respectively located at the origin positions.
The working position of 3 is at a position equidistant from the center of the workpiece W.

At the beginning of the grinding process, the grindstones 16 and 116 are located at the tailstock side ends of the workpiece W, and when started, the grindstone 1 is
6 and 116 approach the workpiece W and make a cut. At that time, the program makes a cut t1 in the grindstone 23 and the grindstone 123.
The cut t2 is given to the table as shown in FIG. 4, the reciprocating motion of the table 3 is started, and the grinding is performed. The cutting of each forward and backward movement of the table 3 is performed by driving the servomotors 52 and 152 by the program of the numerical controller 51, and the finished diameter of the workpiece W is also determined by the numerical controller 51.

In the embodiment, the grindstones 23 and 123 are opposed to each other. However, when the grindstones 23 and 123 are axially displaced so that the cutting amount with respect to the workpiece W is the same, the workpiece W is one of the leading ones with respect to the table feed. Grinding with a grindstone, the other grindstone does not contribute to the grinding but can act as an anti-sway.

[0034]

According to the first aspect of the present invention, when grinding a slender workpiece, (1) the cutting amount of the grindstone can be increased, so that the grinding ability is significantly increased. (2) Even if the cutting amount of the grindstone is increased, the bending moment applied to the workpiece can be reduced by canceling the grinding resistance of the two grindstones.
Alternatively, the number of sway stoppers can be reduced. (3) Compared with the conventional cylindrical grinder, the force applied to the workpiece in the case of the same cutting is small, so that the dimensional error and the shape error of the workpiece due to the deformation of the workpiece become smaller. (4) Since the anti-sway only needs to support the workpiece from one direction, the structure is simple and the adjustment can be performed quickly.

According to the second aspect of the present invention, when the distance between the whetstone correcting tool of each whetstone correcting device and the whetstone in the state of being cut into the workpiece is made equal, each whetstone base is moved back by an equal distance. The grindstone can be corrected. For example, when a rotary diamond dresser is used, there is almost no correction tool wear. Therefore, the diameter of the grindstone is cut equally and the size control of the grindstone is easy.

According to the third aspect of the present invention, since one feed screw has screw portions with different twist directions, both grindstone bases make equal cuts by the rotation of the feed screw, so that the cuts of both grindstones are made separately. There is no need to perform it, and the interlocking device for both whetstones can be easily manufactured.

In the fourth invention of the present invention, since the position of at least one nut in the rotational direction can be adjusted in the third invention, the difference in the relative position of the grindstones of the respective grindstones with respect to the workpiece can be adjusted. The difference in the depth of cut can be easily obtained.

In the fifth aspect of the present invention, each grindstone base is provided with a separate feed device and is driven by a numerical controller, so that the cutting difference between both grindstones can be set and simultaneous cutting action can be performed.

According to the sixth aspect of the present invention, in the fifth aspect, the positions of the respective whetstone bases can be adjusted separately in the axial direction of the workpiece, so that the relative positions of the two whetstones in the axial direction can be adjusted. Therefore, when the work piece has a long length and the grinding portion having a short grinding portion is separated, it becomes possible to grind without greatly changing the stroke position of the table.

In the seventh aspect of the present invention, since both grindstones rotate in the same direction, the moving directions around both grindstones may be the same or opposite to the moving direction of the workpiece peripheral surface. it can.

In the eighth invention of the present invention, since both grindstones rotate in mutually opposite directions, both grindstones are in the same direction with respect to the moving direction of the workpiece peripheral surface, and the peripheral surface of the other grindstone is the same. Moves in the opposite direction. That is, up-cut grinding and down-cut grinding can be combined.

In the ninth aspect of the present invention, since either one of the two grindstones rotates in the forward and reverse directions, both grindstones can rotate in the same direction and both grindstones can rotate in mutually opposite directions. Therefore, any of the grinding methods in the seventh and eighth inventions can be selected.

[Brief description of drawings]

FIG. 1 is a three-view drawing of an embodiment of the present invention, and FIG. 1 is a plan view.

FIG. 2 is a three-sided view of the embodiment of the present invention and is a front view of FIG.

FIG. 3 is a side view of FIG. 1 showing a partial cross section of a third embodiment of the present invention.

FIG. 4 is a side view perpendicular to a workpiece W showing an example of a grinding cut.

FIG. 5 is a side view of the anti-sway.

FIG. 6 is a side view of the sway stopper.

FIG. 7 is a side view showing a partial cross section of another embodiment.

FIG. 8 is a plan view of FIG.

[Explanation of symbols]

W ・ ・ Workpiece 1 ・ ・ Machine base 2 ・ ・ Guide 3 ・ ・ Table 4 ・ ・ Drive device 5 ・ ・ Hydraulic cylinder 6 ・ ・ Workpiece headstock 7 ・ ・ Tailstock 8 ・ ・ Belt device 9 ・ ・ Machining Spindle 10 ・ ・ Electric motor 11 ・ ・ Center
12 ・ ・ Sleeve 13 ・ ・ Center 14 ・ ・ Roller
15 ・ ・ Driving tool 16,116 ・ ・ Grinding stone stand 17,11
7 ・ ・ Guide 18,118 ・ ・ Whetstone stand body 19,11
9 ・ ・ Grinding wheel shaft 21,121 ・ ・ Main motor 22,12
2 ··· Belt device 23,123 ·· Whetstone 24 ·· Feed screw 26,126 ·· Screw portion 27,1
27 ・ ・ Nut 28 ・ ・ Nut case 29 ・ ・ Bearing 31 ・ ・ Second stage worm wheel 32 ・ ・ Second stage worm 33 ・ ・ First stage worm wheel 34 ・ ・ First stage worm 35 ・ ・ Adjustment of both whetstone positions Shaft 36 ····················· s both grindstones positional relationship handle
..Micrometer device 39..Incision handle 4
0 ··· Bearing 41 ··· Fixing screw 42 · · Lever 43,
143 ・ ・ Whetstone correction device 44,144 ・ ・ Whetstone correction tool 45 ・ ・ Whetstone correction tool stand 46 ・ ・ Whetstone correction device 48 ・ ・ V block 49 ・ ・ Receiver 51 ・ ・ Numerical control device 52,152 ・ ・ Servo Motor 53 ... Ball screw 54 ... Ball nut.

Claims (9)

[Claims] 1. A machine base, a table reciprocally mounted on the machine base, a drive unit for the table, a work headstock and a tailstock provided on the table so as to face each other, a headstock and a center. Opposite grindstones provided with two opposing grindstones provided on the machine base so as to be able to move back and forth toward the workpiece on both sides at substantially the same position in the axial direction of the workpiece supported by the push platform, and a drive unit for the grindstone base. Cylindrical grinder equipped with a table. 2. A grindstone correcting device which acts on a grindstone in a retracted position of a grindstone base, and a grindstone correcting tool is arranged at a position opposite to a working position of each grindstone with respect to a workpiece. A cylindrical grinder provided with the facing grindstone according to Item 1. 3. A drive device for a grinding wheel head has a single feed screw arranged in a cutting direction of the wheel head, the feed screw being provided with screw portions having different twist directions from each other and being respectively screwed into the screw portions. A cylindrical grinder having an opposed grindstone stand according to claim 1 or 2, wherein the nut is attached to each grindstone stand. 4. The opposed grindstone head according to claim 3, wherein at least one of the nuts attached to each grindstone head is fixed so that the position in the rotational direction can be adjusted by rotating. Cylindrical grinder equipped. 5. Each grinding wheel head has a driving device, and each driving device connects the grinding wheel head to a servomotor controlled by one numerical controller via a screw feed device. A cylindrical grinder provided with the facing grindstone according to claim 1. 6. The grindstone heads are mounted on the respective saddles so as to move back and forth toward the workpiece, and the saddles are fixed to the guides of the machine base parallel to the table so that their positions can be adjusted. A cylindrical grinder provided with the facing grindstone according to claim 5. 7. A cylindrical grinder provided with an opposite grindstone head according to claim 1, wherein the grindstone rotation directions of both grindstone heads are the same. 8. A cylindrical grinder provided with an opposed grindstone according to any one of claims 1 to 6, wherein the grindstones of both grindstones rotate in opposite directions. 9. The facing motor according to claim 1, wherein at least one of the main electric motors for driving the grindstones provided on the grindstone mounts of both the grindstone mounts is capable of forward and reverse rotation. Cylindrical grinder equipped with a wheel head.