JPS6250241B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lathe that rotates a workpiece and performs cutting with a cutter, and in particular provides a lathe with high machining dimensional accuracy and excellent surface roughness.

In recent years, the demand for precision machined parts has increased, and various lathes have been put into practical use to meet this demand. A conventional cam-type lathe will be explained based on FIGS. 1 and 2. A chuck 3 attached to a spindle 2 of a main shaft portion 1 rotates a workpiece 4. The cutter 5 is fixed by a cutter holder 6 and a cutter rest 7 to an X slide table 9 that moves in the X direction. X slide table 9 and Y slide table 10 are link 1
It is driven by cams 13 and 14 via cams 1 and 12. The stopper 15 is for determining the position of the Y slide table 10.

Here, the X slide table 9 and the Y slide table 10 are the table movable part 1 as shown in FIG.
6 is a structure that moves along a table guide 17. Slide guide 17 and table movable part 16
Since sliding with the screw 1 needs to be performed with high precision, a sliding piece 18 is generally provided between the slide guide 17 and the table movable part 16 as shown in FIG.
Efforts have been made to add preload at step 9. However, if a preload is applied to the sliding piece 18, the frictional force between the slide guide 17 and the movable table part 16 will increase, causing stick slip, which will eventually reduce the accuracy.

Also, when positioning the Y slide table 10 using the stopper 15, the stopper is elastically deformed by the force received from the Y slide table 10, so
The force with which the slide table 10 contacts the stopper 15 needs to be constant in order to keep the amount of elastic deformation constant. In this respect as well, the table movable portion 16
The frictional force generated between and the slide guide 17 is
Since the magnitude of the force with which the Y slide table 10 abuts against the stopper 15 fluctuates, this results in a decrease in accuracy.

Balls or rollers are used instead of the sliding piece 18,
Although it is possible to reduce the frictional force using a rolling mechanism, there are problems such as low rigidity and vibration damping, and dimensional variations in the balls and rollers, making it impractical to use a high-precision mechanism. be.

The present invention aims to eliminate the above-mentioned drawbacks, that is, to provide a lathe that improves the positioning accuracy of the slide table to which the cutter is attached, and has excellent machining accuracy and surface finish.The present invention will be described in detail below according to examples. do.

FIG. 3 is a plan view of the lathe provided by the present invention, and also shows the layout of the hydraulic unit and control device as auxiliary equipment. Figure 4 is a front view of the lathe of the embodiment, and Figure 5 is a front view of the lathe of the embodiment.
The figure is a side view.

3 to 5, a chuck 22 is attached to the spindle 21 of the main shaft portion 20, and a workpiece 23 is gripped by the chuck 22. As shown in FIGS. The spindle 21 has a main shaft motor 24 and a coupling 2.
The pulley 28 receives the rotation of a belt pulley 26 connected by a belt 5 through a flat belt 27, and is rotated. Here, the main shaft motor 24 is fixed to the frame 30 by a bracket 29.

On the other hand, the cutter 31 is attached to a slide table section 34 via a cutter holder 32 and a tool rest 33. The slide table section 34 is composed of an X slide table 35 and a Y slide table 36.

Further, the camshaft motor 37 is attached to the frame 30 via a bracket 38, and the camshaft motor 37
The output is transmitted to the input shaft 43 of the reduction gear 42 via the pulley 39, timing belt 40, and pulley 41. Here, when the input shaft 43 of the reducer 42 rotates, the camshaft 44, which is the output shaft, rotates, and the camshaft 44 rotates.
The X cam 45 and Y cam 46 attached to 4 rotate, and the X slide table 35 and Y slide table 36 are driven via levers 47 and 48. Furthermore, an encoder 49 is connected to the camshaft 44, and a pulse signal that detects the rotational position of the camshaft is sent to the control device 50.

In FIG. 3, a hydraulic unit 51, which is a hydraulic pressure generator, has a main shaft section 20, a slide table section 34,
The control device 50 controls the hydraulic unit 51 and the lathe main body 53 based on signals from the encoder 49.

The configuration of the lathe provided by the present invention has been schematically shown above, and each part will be explained in detail next.

FIG. 6 is a front sectional view of the main shaft portion 20, and the seventh
The figure is a sectional view of B and B' in FIG. 6.

In FIGS. 6 and 7, the spindle 21 is fitted into a radial thrust bush 55 and a radial bush 56 that are press-fitted into a housing 54 with a gap of about 10 μm. A flange 57 for receiving a thrust load is fixed to the spindle 21 with a nut 59 via a collar 58. Radial thrust bush 55
A thrust bush 61 is attached to the flange 57 with a spacer 60 in between.
At this time, the gap between the flange 57 and the thrust bush 61 and radial thrust bush 55 is 10μ.
It should be about m.

Spindle 2 of radial thrust bush 55
There are 4 pockets 62 in the circumferential direction on the surface that mates with 1.
Pockets 63 are also provided at four locations in the circumferential direction on the surface of the radial bush 56 that engages with the spindle 21. The subscripts a, b, c, and d in FIG. 7 are used to distinguish individual pockets. The pockets 62 and 63 have an external hydraulic unit 51.
Hydraulic pressure is supplied from (FIG. 3) through a manifold 64, through first oil passages 65 and 66, and further through shibori 67 and 68.

Furthermore, pockets 69 and 70 are provided on the surfaces of the radial thrust bush 55 and the thrust bush 61 facing the flange 57, and like the pockets 62, hydraulic pressure is supplied from the first oil passage 65 through the shibori 71. .

From the pockets 62, 63, 69, 70 to the gap between the spindle 21 and the radial bushing 56 and radial thrust bushing 55, or from the flange 57
The hydraulic oil flowing out through the gap between the radial thrust bush 55 and the thrust bush 61 is collected into the hydraulic unit 51 through the second oil passage 72. In FIG. 6, a part of the second oil pipe 72 is omitted. In FIG. 6, the hydraulic oil that has leaked further outward from the second oil pipe 72 is transferred to the third oil pipe 73 for drain.
The water passes through and is collected by the hydraulic unit 51.

As described above, the spindle 21 is supported by the radial thrust bush 55, the radial bush 56, and the thrust bush 61 using a hydrostatic fluid bearing structure.

A bracket 74 is fixed to the radial bush 56, and a bearing 75 is attached to the bracket 74 by a collar 76 and a nut 77. The pulley 28 is rotatably attached to the bracket 74 via a bearing 75 by a collar 78 and a holding plate 79. Further, there is a transmission ring 80 between the presser plate 79 and the spindle 21, and the presser plate 79 and the transmission ring 80 are connected by a key 81 made of an elastic body. Further, the transmission ring 80 and the spindle 21 are connected by a key 82.

With the above configuration, when the rotational force is transmitted to the pulley 28 by the flat belt 27 in FIG. 4, the rotational force is transmitted to the spindle 21 by the key 81, the transmission ring 80, and the key 82. At this time, the spindle 21 is supported by a hydrostatic fluid bearing structure, and since an elastic body is used for the key 81, the spindle 21 rotates with less vibration of the axis.

Next, Figure 3, Figure 4, Figure 5, Figure 8, Figure 9
The slide table section 34 will be explained with reference to FIGS. 10, 11, 12, 13, and 14.

FIG. 8 is a plan view of the slide table section 34. The cutter 31 is fixed to a tool rest 33 on a Y slide table 36 by a cutting tool holder 32. Furthermore, the Y slide table 36 is mounted on the X slide table 35.

FIG. 9 is a sectional view of COO'C' in FIG. 8, showing the structure of the X slide table 35. In FIG. 9, guide blocks 84 and 85 are fixed to a base plate 83 on the frame 30. As shown in FIG. On the other hand, the top plate 86
Center block 87, side block 8
8, 89 are installed, and the guide blocks 84, 8
An X-table movable section 90 that slides along 5 is configured. Top plate 86, side blocks 88, 89 and center block 87, guide blocks 84,
A pocket 91 is provided on the surface facing 85, and a pocket 91 is provided from the external hydraulic unit 51 to the manifold 9.
2. Hydraulic oil is supplied through the first oil passage 93 and through the shibori 94. Further, the hydraulic oil that has leaked out from the pocket 91 passes through a second oil passage 95 for recovering hydraulic oil and is collected by the external hydraulic unit 51.

The hydraulic oil that has flowed further outward from the second oil pipe 95 passes through the third oil pipe 96 and is collected by the external hydraulic unit 51.

As described above, the pocket 91, the second oil pipe 95,
The pattern of the third oil pipe 96 is shown in FIG.

In FIG. 10, the shaded area is a raised area and is generally called a land area. A first land portion 97 is provided on the outside of the pocket 91, a second land portion 98 is provided on the outside of the second oil pipe 95, and a third land portion 99 is provided on the outside of the third oil pipe 96. The gaps between the top plate 86, side blocks 88, 89, center block 87, and guide blocks 84, 85 are the lands 9.
7, 98, and 99, it is approximately 10 μm.

With the above configuration, a hydrostatic fluid bearing structure is formed between the X-table movable section 90 and the guide blocks 84, 85. The sliding portion of the Y slide table 36 has almost the same structure.

FIG. 11 is a sectional view of the X table 35 taken along lines D and D' in FIG. An air cylinder 101 is attached to the base block 83 via a block 100. Rod 1 of air cylinder 101
02 has a connector 103 and a bracket 104 at one end.
and center block 87 via block 105.
Fixed. Air is normally supplied to the air cylinder 101 through the air supply ports P1 and 106, and the X table movable section 90 is connected to the arrow X in FIG.
It is being subjected to a force that moves it in the opposite direction.

A stop plate 109 into which a nut 108 screwed with a stop screw 107 is press-fitted into the top plate 86
is installed. There are five stop screws 107 for the X slide table 35. A stopper 110 is attached to the guide block 84. The stopper 110 has five stop screws 10.
There are 5 stop pistons 111 corresponding to 7.

The stop piston 111 has a cylindrical side surface with two opposing flat surfaces, and is housed in the stopper body 112. The stopper 110 has two blocks 113 and 114 for preventing the stop piston 111 from rotating. The stop piston 111 and the blocks 113, 114 have holes 115, 11 larger than the diameter of the stop screw 107.
6,117 are provided. Also stopper 11
0 has air supply ports 118 and 119 on the top and bottom, and when air is supplied to the supply port 118, the stop piston 111 lowers, and the stop piston 11
The hole 115 provided in 1 is located at the location of the stop screw 107. In this state, when the X-table movable part 90 moves in the direction opposite to the arrow X direction, the stop screw 1
Even when the stop screw 107 reaches the position of the stop piston 111, the stop screw 107 enters the hole 115 of the stop piston 111, so the stop screw does not function as a positioner. However, the air supply port 119
When the stop piston 111 is supplied to the stop piston 111, the stop piston 111 is raised, and since the hole 115 of the stop piston 111 does not match the position of the stop screw 107, the stop screw 107 hits the stop piston 111, and the X-table movable part 90 is positioned.

The top plate 86 is provided with a block 121 on which the tip roller 120 of the lever 47 comes into contact.
is moved.

FIG. 12 shows the positional relationship between the stop piston 111, the stopper body 112, and the blocks 113, 114 in cross sections F and F' in FIG.

While the X table movable part 90 is moved by the lever 47, the air cylinder 101 is connected to the supply port P.
However, if air is supplied to the supply port P2, 122 of the air cylinder 101, regardless of the movement of the lever 47, the X table movable part 90 will be moved in the X direction as shown in FIG. In other words, it can be retreated in a direction away from the main shaft portion 20. Therefore, the movement of the slide table section 34 during turning is performed by the lever 47, and the X-table movable section 90 can be moved backward by the air cylinder 101 after the turning process is completed. This allows the cutter to separate from the workpiece after processing, making it easier to load and remove the workpiece.

FIG. 14 shows the configuration of the Y slide table 36 in cross sections E and E' of FIG. 8.

A guide block 1 is attached to the base plate 123 attached to the top plate 86 of the X slide table 35.
24 is installed. On the other hand, a center block 127 and side blocks 128 are attached to a top plate 126 constituting the Y table movable section 125.
A plate 129 is fixed to the side block 128, and a hole 13 is formed in the guide block 124.
0, and a compression spring 131 is installed between the plate 129 and the guide block 124. Guide bar 158 is a guide for compression spring 131. Due to this compression spring 131, the Y table movable portion 125 is constantly subjected to a force that moves it in the direction opposite to the direction of the arrow Y in FIG. Also, the top plate 1
A block 133 is attached to the lever 26 at a position where the tip roller 132 of the lever 48 comes into contact. The stopper 134, the stopper plate 135, and the stop screw 136 function in the same manner as in the case of the X slide table 35.

In this embodiment, the stroke of the X table movable section 90 is large and the stroke of the Y table movable section 125 is small, so the X slide table 35 is equipped with an air spring using an air cylinder 101, and the Y slide table 36 is equipped with a compression spring 131. However, if necessary, the compression spring of the Y slide table 36 can be replaced with an air spring.

Next, the cam drive section shown in FIG. 15 will be explained. FIG. 15 is a sectional view of GOO'G' in FIG. 3.
A lever 47 that acts on the X slide table 35 and a lever 48 that acts on the Y slide table 36.
is rotatably fitted to a lever shaft 137, and the lever shaft 137 is attached to the frame 30 by a bracket 138. Rollers 120 and 132 are rotatably attached to the tips of the levers 47 and 48 by pins 139. One end of the lever 47 contacts the X slide table 35, and the other end contacts the X cam 45.
comes into contact with. Similarly, one end of the lever 48 contacts the Y slide table 36, and the other end contacts the Y cam 46. X cam 45 and Y cam 46 are connected to pin 140,
141 to a transmission collar 142, and the transmission collar 142 is connected to a camshaft 44 by a key 143a. The camshaft 44 is attached to a bearing holder 143 attached to the frame 30 via bearings 144 and 145. The retainer ring 146, spacers 147, 148, and nut 149 hold the bearings 144, 145 on the camshaft 4.
4 and the bearing holder 143. The worm 1 is further attached to the camshaft 44 by a key 150, a spacer 151, and a nut 152.
A wheel 154 is attached which meshes with 53.

The bearing holder 143 has the reducer case 1
55, an encoder 49 is attached via brackets 156 and 157, and this encoder 49 is connected to the camshaft 44 by a connector 159. As a result, the rotational position of the camshaft 44 is determined by the encoder 49.
Detected by Note that the bearing 160 is for suppressing vibration of the tip of the camshaft 44.

The shaft of the worm 153 in FIG. 15 is the input shaft 43 shown in FIG. 5, and receives the rotational force of the camshaft motor 37. Now, when the camshaft motor 37 is rotated, the rotational force is applied to the pulley 39 and the timing belt 4.
0 is transmitted to the input shaft 43 via the pulley 41.
As a result, the worm 153 rotates, and the wheel 1
54, cam shaft 44, X cam 45, Y cam 4
6 rotates. At this time, the X slide table 35
The Y slide table 36 is driven by levers 47 and 48 via rollers 120 and 132 that contact the X cam 45 and Y cam 46. Further, the rotational position of the camshaft 44 is detected by an encoder 49.

Next, the hydraulic circuit of the hydraulic unit 51 that supplies hydraulic oil to the hydrostatic fluid bearings of the main shaft portion 20 and the slide portion 34 will be explained with reference to FIG.

Hydraulic oil sucked up from a tank 163 by a pump 162 driven by a motor 161 passes through a filter 164 and is pressurized by the pump 162 . The relief valve 165 is for keeping the pressure constant, and the pressure is displayed by a meter 166. The hydraulic pressure coming out of the pump 162 is transferred to the switching valves 167 and 168.
One side is supplied to the main shaft section 20 and the other side is supplied to the slide table section 34.

The hydraulic pressure coming out of the switching valve 167 passes through the valves 67, 68, and 71 shown in FIG.
3,69,70. Spindle 21, flange 57 and radial thrust bush 5
5, the pockets 62, 63, 6 through the gap between the radial bush 56 and the thrust bush 61.
The hydraulic oil flowing out from the oil pipes 9 and 70 passes through the second oil pipe 72 and is collected into the tank 163. The hydraulic oil that has leaked further outside the second oil pipe 72 is collected into the tank 163 through the third oil pipe 73.

On the other hand, the hydraulic pressure coming out of the switching valve 168 is supplied to the pocket 91 through the first oil passage 93 and through the shibori 94, as shown in FIG. Most of the hydraulic oil flowing out of the pocket 91 is recovered by the second oil pipe 95. The hydraulic oil further flowing out from the second oil pipe 95 is recovered by the third oil pipe 96. At this time, a pump 170 driven by a motor 169 is connected to the third oil pipe 96 , and the hydraulic oil in the third oil pipe 96 is forcibly sucked by the pump 170 and collected into the tank 163 .

Generally, a sliding mechanism with a hydrostatic fluid bearing structure has the disadvantage that hydraulic oil tends to leak to the outside of the device, and to prevent this, the device becomes large in size. pump 1
By providing 70, hydraulic oil will not leak to the outside of the device, and the slide table portion can also be designed compactly.

Since the lathe provided by the present invention has the configuration described above, it has the following features.

(1) In the lathe provided by the present invention, when cutting a workpiece rotated by the main shaft section 20, the slide table section 34 to which the cutter is attached is mounted on the cam 4.
5, 46 and levers 47, 48.

First, in order to cut a cylindrical surface, the Y table movable part 125 has a stop screw 136 and a stopper 134.
The X-table movable section 90 is driven by the lever 47 along the cam 45.
Here, the stop screw 136 and the stopper 134 come into contact with each other due to the force generated by the spring 131. In addition, the Y table movable part 125 and the guide block 1
24 has a hydrostatic fluid bearing structure, so the frictional force is small, and the force induced by the spring 131 is directly applied between the stop screw 136 and the stopper 134. For this reason, the stop screw 136
There is little variation in the amount of elastic deformation of the stopper 134, and the positioning accuracy of the Y table main body 125 is improved.
Especially the repeat accuracy is good.

Next, to cut the end face, the X table movable part 9
0 is positioned by the stop screw 107 and the stopper 110, and the Y table movable part 125 is driven by the lever 48 along the cam 46.
Here, the stop screw 107 and the stopper 110 come into contact with each other due to the thrust generated by the air cylinder 101. In addition, the X table movable part 90 and the guide block 8
4 and 85 (first guide block) has a hydrostatic fluid bearing structure, so the frictional force is small, and for the same reason as the Y table movable part 125,
The positioning accuracy of the X-table movable part 90, especially the repeatability, is good.

As described above, since the positioning accuracy of the slide table portion 34, that is, the cutter 31 is high, the lathe provided by the present invention can perform cutting with high precision.

(2) Furthermore, in the lathe provided by the present invention, the X slide table 35 and the Y slide table 36 are provided with a plurality of stop screws 107, 136 and stoppers 110, 134, respectively, so that the cutter can be positioned accurately at multiple points. can do.

(3) Furthermore, in the lathe provided by the present invention, an air cylinder is provided as a means for generating a force for abutting the stop screw against the stopper, so that the abutting force is constant. Therefore, the amount of elastic deformation of the stopper and the stop screw is constant, and the positioning accuracy, especially the repeatability, of the X table movable part and the Y table movable part is increased.

(4) Furthermore, in the lathe provided by the present invention, a second oil passage 95 for returning hydraulic oil to the hydraulic unit 51 is provided outside the pocket 91 of the hydrostatic fluid bearing configured in the slide table portion 34, and a second oil passage 95 is provided for returning hydraulic oil to the hydraulic unit 51. Since a third oil pipe 96 is provided outside the third oil pipe 95 and a pump 170 is provided to suck the hydraulic oil from the third oil pipe 96, the slide table section 34 can be designed compactly without leaking the hydraulic oil to the outside. .

At this time, since most of the hydraulic oil flowing out from the pocket 91 is recovered in the second oil pipe 95, the pump 170 provided in the third oil pipe 96 may have a relatively small capacity.

(5) Furthermore, in the lathe provided by the present invention, the workpiece 2
The main shaft part 20 that rotates the blade 3 and the slide table part 34 that positions the cutter 31 have hydrostatic fluid bearings, which have high vibration absorption properties, making it difficult for vibrations from external sources such as the motor to be transmitted to the cutter or the object to be cut. This allows cutting with high precision and an excellent surface finish.

(6) Furthermore, in the lathe provided by the present invention, since the X table movable section 90 and the Y table movable section 125 are driven by the levers 47 and 48 along the cams 45 and 46, malfunctions are less likely.

(7) Furthermore, in the lathe provided by the present invention, the rollers 120 are attached to the tips of the levers 47 and 48 that act on the X table movable section 90 and the Y table movable section 125.
132, the X table movable part 9
The forces driving the 0 and Y table movable parts 125 are in directions parallel to the slide guides 84, 85 (first guide block) and the slide guide 124 (second guide block), respectively. Therefore, the straightness of the X table movable section 90 and the Y table movable section 125 is good.

As described above, in the present invention, a second oil passage is provided outside the pocket of the hydrostatic fluid bearing configured in the slide table portion, and a second oil passage is provided for returning hydraulic oil to the hydraulic unit.
A third oil pipe is provided outside the oil pipe, and a pump is provided to suck the hydraulic oil from this third oil pipe, so that the hydraulic oil does not leak outside, and the slide table part can be designed compactly. Can be done. Therefore, a hydrostatic fluid bearing structure can be created between the table movable part and the guide block, reducing the frictional force on the sliding part, and applying the force induced by the spring directly between the stop screw and the stopper. be able to. This reduces variation in the amount of elastic deformation between the stop screw and the stopper, improving the positioning accuracy of the table body, that is, the repeatability of the cutter.

As can be seen from these results, the present invention provides a lathe that can perform cutting with high accuracy and an excellent finished surface.

[Brief explanation of the drawing]

Figure 1 is a schematic plan view of a conventional cam-type lathe, Figure 2
The figures are a sectional view taken along lines A and A' in Fig. 1, Fig. 3 is a plan view of a lathe according to an embodiment of the present invention, Fig. 4 is a front view of the same partial cross section, and Fig. 5 is a side view of the same partial cross section. figure,
Fig. 6 is a front sectional view of the main shaft, Fig. 7 is a sectional view of the main shaft taken along lines B and B' in Fig. 6, Fig. 8 is a plan view of the slide table, and Fig. 9 is a sectional view of the main shaft. figure
A sectional view taken along the line COO'C' is a sectional view of the X slide table, Figure 10 is a pattern diagram of the hydrostatic fluid bearing in the slide table section, and Figure 11 is a sectional view taken along lines D and D' in Figure 8 of the slide table. Figure 12 is a cross-sectional view of the stopper along lines F and F' in Figure 11, and Figure 13 is a cross-sectional view of the slide table part along lines D and D' in Figure 8. The figure is E in Figure 8,
Cross-sectional view of the slide table part in E′ cross-sectional view, 1st
FIG. 5 is a cross-sectional view taken along line GOO'G' in FIG. 3, and is a cross-sectional view of the cam drive section, and FIG. 16 is a hydraulic circuit diagram of the lathe of the same embodiment. 4, 23... Work to be cut, 1, 20... Spindle part,
5,31...Knife, 34...Slide table section, 9,35...X slide table, 10,3
6...Y slide table, 84, 85, 124
...Guide block, 13, 14...Cam, 45
...X cam, 46...Y cam, 107,136...
...stop screw, 110, 134...stopper,
47, 48... Lever, 120, 132... Roller, 101... Air cylinder, 65, 6
6,93...1st oil road, 72,95...2nd oil road, 73,96...3rd oil road, 62,63,6
9, 70, 91...Pocket, 51...Pressure generating unit.

Claims (1)

[Claims] 1. A main shaft portion rotatably holding a work material;
An X slide table and a second
a Y slide table that is movable along a guide block in a direction perpendicular to the axis of the main shaft portion, a slide table that holds a blade for cutting the work material and is movable in a plane, and an X slide table. and a stop screw provided on the Y slide table so that its length can be adjusted; a stopper provided on the guide block at a position corresponding to the stop screw; and the X slide table and the Y slide table are each attached to abut against the stopper. It consists of an X-slide table and a first
A hydrostatic fluid bearing is configured between the guide block, the Y slide table, and the second guide block, and the hydrostatic fluid bearing is provided with a first oil passage that guides pressurized fluid to a pocket to which fluid pressure is applied, A second oil pipe is provided on the outside of the pipe to return the working fluid to the pressure generating unit, a third oil pipe is provided on the outside of the second oil pipe, and a means for sucking the working fluid from the third oil pipe is provided. A lathe characterized by: 2. A plurality of stop screws are provided on each of the X slide table and the Y slide table, and a stopper is provided that selects and abuts the stop screws to position the X slide table and the Y slide table. A lathe according to claim 1. 3. The lathe according to claim 1, wherein an air cylinder is provided as means for biasing the X and Y slide tables so as to abut each stopper. 4. The lathe according to claim 1, wherein the main shaft portion is provided with a hydrostatic fluid bearing. 5. The lathe according to claim 1, wherein the X and Y slide tables are driven by a lever driven by a cam. 6. The lathe according to claim 5, characterized in that a roller is provided at the tip of the lever.