JPH0337886Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a centerless grinding machine for ultra-precision grinding of workpieces mainly using a super-abrasive grindstone.

[Prior Art] In general, a centerless grinding machine is composed of a grinding wheel, an adjusting wheel, and a blade positioned between them to support a workpiece.The adjusting wheel receives the workpiece supported by the blade, and the adjustment wheel Rotate and grind to desired dimensions.

In this case, the grinding wheel is fixed to a rotating shaft via a tapered flange or the like, and a drive pulley is attached to one end of the rotating shaft to rotate the grinding wheel. Furthermore, when the grinding wheel wears out, the grinding wheel head is corrected by the amount of wear and grinding is performed. The guide surface of the grindstone head is a dynamic pressure sliding guide surface, a low friction rolling guide surface, or a static pressure guide surface. Even when performing precision grinding using a superabrasive grindstone, these machines manufactured for general purposes are also used.

[Problems to be solved by the invention] In grinding, the machining accuracy and machining efficiency of a workpiece are controlled by the support and drive accuracy and rigidity of the workpiece and the accuracy and rigidity of the grinding wheel (including the rotating shaft). big.

When using a large superabrasive grinding wheel on a centerless grinder, high-precision grinding wheel correction requires the use of a dedicated correction machine outside the machine. When the grindstone finished with this correction machine is removed from the correction machine and reinstalled in the processing machine, there must be no change in accuracy such as increased runout of the outer periphery due to installation errors caused by transfer. With the conventional structure, it is not possible to reproduce the grindstone accuracy required for ultra-precision grinding when a grindstone or grindstone unit that has been modified outside the machine is transferred to the inside of the machine.

Furthermore, in order to control the dimensions of the workpiece with high precision, the position of the grindstone head must be accurately controlled.
If a dynamic pressure sliding surface is used as a guide surface for positioning, accurate positioning cannot be achieved due to the influence of frictional force. In the case of a low-friction guide surface such as a rolling guide, the rigidity in the guide direction is low, so chatter vibrations are likely to occur, making it unsuitable for high-precision, high-efficiency grinding.

[Means for Solving the Problems] The present invention was devised in order to eliminate this problem in view of the above-mentioned circumstances.The present invention has been devised in order to eliminate this problem. In addition to increasing rigidity and compactness, it is intended to reliably reproduce the revised grinding wheel system. Furthermore, preload is applied to the hydrodynamic slide guide surface as the feed guide surface of the grinding wheel head and the adjustment wheel head using a hydrostatic pressure bearing.
The structure is designed to improve accuracy and rigidity by providing a guide gap O, and is equipped with a servo mechanism that detects the frictional force on the feed guide surface and cancels it to improve the fine positioning accuracy of the grindstone head, improving the machining accuracy and machining efficiency of the workpiece. The present invention provides a centerless grinding machine that aims to improve the grinding speed and simplify the mechanical mechanism.

[Operation] Consists of a grinding wheel on a rotating sleeve that is hydrostatically bearing on a spindle fixed to a grinding wheel head, an adjusting whetstone that is hydrostatically bearing on a spindle that is also fixed to an adjusting wheel head, and a blade that supports the workpiece. The workpiece is supported in the V-shaped valley formed by the surface of the grinding wheel and the blade, and the grinding wheel is rotated to give cutting feed motion to the grinding wheel table 5 using the above-mentioned guide surface and positioning mechanism. This grinds the outer periphery of the workpiece.

[Example] Next, an example of the centerless grinding machine according to the present invention will be specifically described with reference to the accompanying drawings.

The centerless grinding machine A mainly consists of a bed 1, a grinding wheel 2, an adjusting wheel 3, and a blade 4 that supports the workpiece W. The centerless grinding machine A is mainly composed of a bed 1, a grinding wheel 2, an adjusting wheel 3, and a blade 4 that supports the workpiece W. The grinding wheel 2 of the grinding wheel sleeve U has a static pressure radial bearing and a thrust bearing on a spindle 20 (described later) fixed to the grinding wheel head 5, and the outer periphery of the workpiece W is cut by the cutting feed movement of the grinding wheel head 5. Grind.

The blade 4 is mounted on a grinding table 8 which is located between a grinding wheel head 5 and an adjustment wheel head and is attached via a grinding table mount 7 fixed to the bed 1.

The grinding wheel sleeve U is placed on the semicircular support parts 5a, 5b at the top of the grinding wheel head 5, and is covered with the lower semicircular support parts 9a, 9b of the upper cover 9, and the grinding wheel head is tightened by tightening bolts. The grinding wheel head 5 is guided to a guide surface provided at the bottom of the grinding wheel head 5 via a feed screw shaft 11 by rotating a drive motor 10. and can move in the left and right directions in FIG.

The grinding wheel 2 is driven by a belt 12 (described later) by a drive motor (not shown) separately installed outside the bed 1.
is rotationally driven via an intermediate shaft.

13 is a general grindstone correction device provided on the grindstone 2 side for correcting the surface of the general grindstone.

The stationary spindle of the adjustment whetstone 3 is attached to the adjustment whetstone stand 6, and this stationary spindle is also housed in a semicircular support part on the adjustment whetstone stand 6, and this is covered by the lower semicircle support part of the upper cover 15 and tightened. Fixed with bolts.

By operating the handle 16 or rotating the feed motor, the adjusting whetstone head 6 is guided by a feed guide surface provided at the bottom of the adjusting whetstone head 6 via a feed screw, and can be moved in the left-right direction in FIG. 1. 1
7 is a correction device for correcting the surface of the adjustment grindstone 3, and 18 is a drive motor for the adjustment grindstone 3, which is rotationally driven by the drive motor 18 via a reduction gear and an intermediate shaft.

Next, what is shown in FIG. 2 is an explanation of the grinding wheel sleeve and the grinding wheel head.
A semicircular support part 5 with a and 20b provided on the grinding wheel head 5
a, 5b, and the upper portions of both ends of the spindle 20 are provided on the lower surface of the upper lid 9.
It is fixed to the grinding wheel head 5 by covering it with a bolt and tightening it with a tightening bolt. This spindle 20 accommodates the grinding wheel sleeve U inside the grinding wheel head 5, and the grinding wheel sleeve U is supported by a hydrostatic radial bearing and a thrust bearing on the (stationary) spindle. The grinding wheel sleeve U is composed of a rotating sleeve 21 and a grinding wheel 2 that is fitted onto the outer peripheral surface of the rotating sleeve 21 and fixed by tightening bolts 23 from the side via a movable flange 22. A rotary drive pulley part 24 is provided to hang the belt 12, and the inner peripheral surface 21 of the rotary sleeve 21 is provided.
a is a rotating static pressure radial bearing surface, and the left end surface 21b of the rotating sleeve 21 is the mounting reference surface for the thrust bearing plates 25 and 26, and the rotating sleeve 2 is held stationary by the belt 12.
1 is rotationally driven. In addition, a labyrinth seal S is provided on the rotating pulley to prevent grinding fluid from entering. The spindle 20 has a protrusion thrust flange 20c on the left side for forming a thrust bearing, and this thrust flange 20c
C has annular thrust pockets 27 and 28 on both sides.
is provided.

Pressure oil for the bearings to be supplied to the thrust pockets 27 and 28 is supplied from a supply hole 29 and sent to the pocket 28 via a built-in filter 30, a distribution line 31, and a throttle resistor 32. Also, the refueling of the pocket 27 and the radial pocket 33 of the spindle 20 are performed in the same manner. In addition, the oil flowing out from the bearing passes through the recovery pipes 34, 35, 36, and 37 to the recovery hole 3.
It is collected outside from 8.39.

The stationary spindle 20 has two sets of radial pockets 33 arranged on its outer periphery (see FIG. 3) in the axial direction. Pressure oil is supplied from the supply holes 29 and 40, and the filter 3
0, 41, pipes 31, 42, and a restriction to be supplied to each pocket. The sea flowing out from between the bearings between the outer periphery of the spindle 20 and the inner periphery 21a of the rotating sleeve 21 collects in the inner annular spaces 43, 44, 45 and passes through the oil recovery pipes 46, 47, 48 and 36, 37. The oil is collected from the collection holes 38 and 39, and the collection annular space is sealed with oil seals 49 and 50 to prevent the oil from flowing out from there.

In this way, a static pressure radial bearing is constructed between the outer periphery of the stationary spindle 20 and the inner periphery of the rotating sleeve 21 of the grindstone sleeve U, and the rotating sleeve 21 is positioned and supported on the stationary spindle without contact.

Next, the feeding structure of the grinding wheel head will be explained with reference to FIG. 4. On the rear side of the grinding wheel head 5, there is a feed screw nut 51 located at the center height of the grinding wheel 2, and a feed screw rod 11 screwed into the feed screw nut 51. The tip of the is attached. The nut 51 is a preloaded double nut and has no play. The distal end of the feed screw rod 11 is supported in a non-contact manner by a hydrostatic thrust bearing 53 and a hydrostatic radial bearing 54 provided within a screw mounting bracket 52 attached to the bed 1. An internal gear coupling plate 5 is provided on the end surface of the feed screw shaft 11.
5 is installed, and the drive side external gear plate 56
The drive motor 10 is connected to the externally toothed gear plate 56 via a speed reducer, and the internally toothed gear coupling plate 55 can freely move in the axial direction, yet no thrust load is transmitted. There is.

Therefore, the feed screw shaft 11 is driven by the drive motor 10, etc.
By rotating the wheel, the whetstone head 5 can be moved left and right. At this time, a frictional force acts on the feed guide surface provided below the grindstone head 5, and a sliding force corresponding to this frictional force is applied to each part.

That is, when a large frictional force is applied, the screw mounting bracket 52 is elastically deformed from side to side, deteriorating the positional accuracy. It also causes the position to become unstable when the feeding direction is reversed.

Therefore, a hydraulic actuator B is provided at the lower part of the grindstone head 5 where the feed guide surface is located. A piston rod 57 whose tip is fixed to the grindstone head 5 is slid into a cylinder 59 fixed to an actuator mounting bracket 58 fixed to the bed, and the output pressure oil of the servo valve 60 is sent to the pressure chamber 59a or 59b.

That is, since the mounting bracket 52 is deformed, the grindstone head 5 cannot be moved by the screw rotation angle. Therefore, the hydraulic actuator detects the force applied to the feed screw shaft 11, generates the force required to move the grindstone head, operates the servo valve 60 so that the force applied to the feed screw shaft 11 is always zero, and removes the mounting bracket. The deformation of the grindstone head 5 is eliminated and the grindstone head 5 is moved by the rotation angle. This force applied to the feed screw shaft will be explained with reference to FIG.

The pressure difference between opposing hydrostatic thrust bearings is proportional to the force on the lead screw. A differential pressure sensor 61 electrically detects the pressure difference and provides a correction signal to the servo valve 60 via a servo amplifier 62.

Figure 6 shows the structure of the grinding wheel head and bed guide surface.
1a is provided, and the lower surface of the whetstone head 5 is a guide surface 5.
c and 5c, forming a dynamic pressure sliding guide surface.
The whetstone head 5 has a T-shaped protrusion 5d at the lower part of the center, and the left and right horizontal parts of the protrusion 5d are opposed to two protrusions 1b, 1b provided at the center of the bed 1.

Static pressure pockets 61, 61 are provided in the horizontal part of the protrusion 5d at positions relative to the protrusions 1b, 1b, and the grinding wheel head 5 is
Installed on the terminal 62 from the supply hole 63 to the aperture 6
4. Pressure oil is supplied through the pipe line 65. Therefore, the pocket pressure of these pockets 61, 61 is
is pressed downward to provide additional preload to the dynamic pressure sliding guide surfaces 5c, 5c.

The terminal 62 has a static pressure pocket 66 and is supplied with pressure oil via a restriction 67. This pocket 66 and the side surface of the bed 1 constitute a hydrostatic bearing. The reaction force of the pocket pressure presses the vertical guide surface 5e of the grindstone head 5 against the vertical guide surface 1c of the bed 1, and serves as a preload force for this dynamic pressure sliding guide.

Further, by changing the oil supply pressure of the supply hole 63, the preload force can be easily adjusted.

A plurality of these preload pockets are arranged in the guiding direction so that preload can be applied uniformly.

[Effects] As described above, the present invention is configured with a grinding wheel, an adjusting wheel, and a blade for supporting the workpiece on the bed, and the workpiece is supported by the surfaces of the adjusting wheel and the blade, and one of the grindstones is supported. In a centerless grinder that grinds the outer periphery of a workpiece by applying a cutting feed motion to the grindstone head, the grinding wheel and adjustment wheel are fitted onto the outer periphery of a rotating sleeve that has a rotation drive unit at one end. The inner peripheral surface of the rotating sleeve is supported by a hydrostatic radial bearing and a thrust bearing on a spindle whose both ends are tightened and fixed to a grinding wheel head and an adjusting wheel head.
Furthermore, it is characterized by providing means for uniformly applying a preload to the dynamic pressure sliding guide surface of the feed guide of the grinding wheel head and the adjusting wheel head using static pressure bearings, and furthermore, it is equipped with a servo mechanism that cancels the frictional force on the feed guide surface. In this centerless grinding machine, the grinding wheel and the adjusting wheel are statically supported on a spindle whose both ends are tightened and fixed to a grinding wheel head or an adjusting wheel head, and the sleeve rotates to achieve high rigidity and miniaturization. Even if a product that has been corrected using an external correction machine with the same structure (shaft fixed structure) is returned to its original grinding wheel head, there will be no installation error during movement as long as the inner diameter of the sleeve does not change.
In addition, the feed guide of the grinding wheel head is preloaded by a hydrostatic bearing on the hydrodynamic sliding guide surface, reducing the guide clearance to zero, achieving high precision and high rigidity, and a servo mechanism that cancels the frictional force on the feed guide surface of the grinding wheel head. This has the effect of allowing accurate fine positioning, improving machining accuracy and machining efficiency, and simplifying the structure.

[Brief explanation of the drawing]

The drawings show an embodiment of the centerless grinding machine according to the present invention, and FIG. 1 is a front view, FIG. 2 is a vertical cross-sectional view of the grinding wheel side showing the grinding wheel sleeve, the grinding wheel sleeve, and the grinding wheel head, and FIG. Figure 3 is a cross-sectional view taken along the X-X line in Figure 2, Figure 4 is a partial longitudinal cross-sectional view of the cutting feed section of the grinding wheel head, and Figure 5 is an explanatory diagram of the device for detecting the force applied to the feed screw shaft. , FIG. 6 is a longitudinal sectional view showing the structure of the grindstone head and the bed guide surface. 1...Bet, 2...Grinding whetstone, 3...Adjustment whetstone, 4...Blade, 5...Grinding whetstone stand, 5a,
5b...Support part, 6...Adjusting grindstone head, 7...Grinding table mounting base, 8...Grinding table, 9, 15...Top lid, 9
a, 9b... Support part, 10, 18... Drive motor, 11... Feed screw shaft, 12... Belt, 1
3, 17... Correction device, 16... Handle, 20
... Spindle, 20a, 20b ... Spindle end, 21 ... Rotating sleeve, 21a ... Inner peripheral surface, 22 ... Movable flange, 24 ... Pulley part,
25, 26... Thrust bearing plate, 27, 2
8, 33... Pocket, 29, 40, 63... Supply hole, 30, 41... Filter, 31, 42, 6
5, 67... Distribution line, 32, 64... Throttle resistance, 34, 35, 36, 37, 46, 47, 48
...Recovery pipe line, 38, 39...Recovery hole, 43,4
4, 45...〓 between, 51... feed screw nut, 5
2...Mounting bracket, 53, 54...Bearing,
55...Internal gear coupling plate, 56...
...External gear plate, 57...Piston rod,
58...Mounting bracket, 59...Cylinder, 6
0... Servo valve, 61, 66... Pocket, 62
...Terminal, A...Centerless grinding machine, B...
Hydraulic actuator, U... Grinding wheel sleeve, W
...workpiece.

Claims (1)

[Scope of utility model registration request] A grinding wheel, an adjusting wheel, and a blade for supporting a workpiece are provided on a bed, the workpiece is supported by the surfaces of the adjusting wheel and the blade, and cutting feed motion is applied to a grindstone head that supports one of the grindstones. In a centerless grinding machine that grinds the outer periphery of a workpiece, the grinding wheel and the adjusting wheel are fitted onto the outer periphery of a rotating sleeve that has a rotation drive unit at one end, and the inner peripheral surface of the rotating sleeve is placed on the grinding wheel head. , is supported by a hydrostatic radial bearing and a thrust bearing on a spindle whose both ends are tightened and fixed to the adjustment whetstone head, and a uniform preload is applied to the hydrodynamic sliding guide surface of the feed guide of the grinding whetstone head and the adjustment whetstone head by the hydrostatic pressure bearing. A centerless grinding machine characterized in that it is equipped with a means for applying friction and a servo mechanism that cancels out the frictional force on the feed guide surface.