JPH10118922A - Feeding mechanism for grinding wheel stand in grinding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provided a grinding wheel stand feeding mechanism in a grinding machine corresponding to a high speed feeding which can face to the grinding resistance acting to the grinding wheel strongly and also miniaturize the grinding wheel stand, especially the grinding wheel stand feeding mechanism suitable for a cam grinding machine. SOLUTION: The screw shaft 24 for feeding a grinding wheel stand 3 is formed as a high lead male screw and a nut device 20 screwed thereto is constituted as a static pressure nut device providing a static pressure bearing part. Thereby, the entire length of the screw feeding mechanism consisting of the screw shaft 24 and the static pressure nut device is shortened and the screw feeding mechanism is arranged in parallel with a straight line guide part 2 in the rear part of the grinding wheel stand 3 so that the screw shaft 24 is approached from the straight line guide part 2 for guiding the lower surface of the grinding wheel stand 3 to the grinding wheel shaft side on the grinding wheel stand 3. The installation position of the screw shaft 24 in the axis direction of the grinding wheel shaft is leaned near the grinding wheel G side than the lateral guide plate of the straight line guide part 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feed mechanism for a wheel head in a high-efficiency grinding machine for cutting a workpiece at a high speed with a grinding wheel to grind the workpiece.

[0002]

2. Description of the Related Art In recent years, in the field of grinding, as in the field of cutting, further improvement in productivity has been demanded. In the grinding of a camshaft used in an automobile engine, a so-called plunge grinding method in which a grinding wheel is cut from a camshaft in a radial direction of a cam rotated on a main shaft axis is employed, and the cam machining efficiency is increased. Attempts have been made to increase the plunge cutting feed speed of the grinding wheel with respect to the cam in order to improve the cam speed.

In this type of conventional cam grinder, a grindstone table is slidably guided along a pair of guides on a bed, and the rotational driving force of a servomotor fixed to the bed is supplied to the grindstone via a ball screw mechanism. It uses a feed mechanism that transmits to the table and moves the grinding wheel back and forth. More specifically, the nut device of the ball screw mechanism is fixed via a bracket to the lower surface of the wheel head between a pair of guided surfaces formed on the wheel head corresponding to the pair of guide surfaces on the bed. You. For this reason, the axis of the ball screw which is screw-engaged with the nut device and the grindstone shaft which is rotatably supported on the upper front side of the grindstone table are spaced apart by a considerable distance.

The ball nut device is arranged in tandem with a spacer interposed to remove backlash.
It is composed of two nut members. Further, in a grinding wheel stand of a conventional cam grinding machine, an electric motor is disposed on the rear upper surface, and the grinding wheel shaft is driven via a pair of pulleys and a belt.

[0005]

In the feed mechanism for a grinding wheel head constructed as described above, the ball nut device in which two nut members are arranged in tandem not only has a long overall length but also has a long ball nut device. The effective screw portion of the ball screw engaged with the ball screw device is inevitably lengthened. As a result, the overall length of the ball screw device is increased, and from the viewpoint of reducing the required floor area of the cam grinder, the ball screw device is disposed below the grindstone table. It had to be arranged in parallel with the wheel head.

Further, since the overall length of the ball screw is long, when the ball screw is rotated at a high speed, the influence of the rotational runout of the ball screw becomes remarkable, and the influence of the rotational runout is the feed accuracy of the grinding wheel head, and furthermore, the ground surface of the workpiece. This is a factor that lowers the processing accuracy. In order to solve this problem, it is necessary to provide a run-out absorbing member such as a floating plate between the nut device and the grindstone table, so that the grindstone table feed mechanism is complicated.

Further, since the axis of the ball screw arranged at the lower part of the grinding wheel head and the axis of the grinding wheel shaft arranged at the upper part of the grinding stone head are separated from each other by a considerable distance in the vertical direction, they are fixed to one end of the grinding stone shaft. The grinding force acting on the grinding point of the set grinding wheel generates a moment that causes the grinding wheel head to be deviated in a plane perpendicular to the grinding wheel axis, centering on the engagement point between the nut device and the ball screw, and this moment causes the pitching of the grinding wheel head. It induces movement and hinders smooth feeding, which is a factor of reducing the machining accuracy of the cam machining surface. This problem is particularly remarkable in a cam grinding machine in which a grinding point reciprocates across a horizontal plane including a work spindle and a grinding wheel axis.

[0008] Further, in order to enable high-speed feeding of the grinding wheel head, it is desirable to reduce the mass of the grinding wheel head itself. However, the grinding wheel head in the conventional cam grinder is equipped with a grinding wheel shaft drive mounted at the rear thereof. In order to secure the installation space for the electric motor, it has to be long, making it difficult to reduce the size of the grinding wheel head. Therefore, the main object of the present invention is to reduce the total length of the wheel head feed nut device and the length of the effective screw portion of the screw shaft engaged with the nut device,
This enables tandem arrangement with the grinding wheel head, and also reduces the adverse effects caused by the rotational runout of the screw shaft, thereby eliminating the need for a runout absorbing member such as a floating plate used in the conventional apparatus. An object of the present invention is to provide a grindstone feed mechanism for high-speed feeding.

Another object of the present invention is to provide a wheel head feed mechanism, preferably a wheel head feed mechanism capable of miniaturizing the apparatus including the wheel head and its feed mechanism, and capable of countering the moment of turning the wheel head by the grinding resistance acting on the wheel. Another object of the present invention is to provide a wheel head feed mechanism for a cam grinder. Still another object of the present invention is to provide a wheel head feed mechanism suitable for a wheel head that can reduce the overall length in the feed direction to reduce the mass accompanying high-speed feed.

[0010]

SUMMARY OF THE INVENTION The above-mentioned first object of the present invention and related objects are solved and achieved by a feed mechanism for a grinding wheel base in a grinding machine according to the present invention. According to the invention as set forth in claim 1, the screw shaft for feeding the grinding wheel head is formed with a male screw having a large lead, and the linear guide portion is provided immediately behind the grinding wheel head which can advance and retreat along the linear guide portion on the base. And are arranged in parallel. The nut device that is screwed with the screw shaft includes a radial static pressure bearing portion that radially supports the screw bottom of the screw shaft in the radial direction with a static pressure of the hydraulic pressure, and a hydraulic static pressure on the flank of the thread of the screw shaft. And a thrust hydrostatic bearing for applying pressure. Thus, when grinding resistance acts on the grinding wheel on the grinding wheel shaft supported at the upper front end on the grinding wheel head, the screw shaft applies a propulsive force against the grinding resistance from directly behind the grinding wheel head, and the pitching motion of the grinding wheel head Acts to suppress the Further, the nut device acts so as to attenuate rotational runout and vibration in relative rotation with the screw shaft by the radial and thrust bearing portions.

Preferably, the helical thread of the female screw of the nut device is formed such that the top surface thereof has a flat axial cross section, and the helical screw bottom of the male screw is formed on the top surface of the helical female screw. Is formed at a static pressure of hydraulic pressure. In this case, in order to provide a centering function, the radial hydrostatic bearing portion has at least three or more hydrostatic bearing pockets equally distributed in the circumferential direction of the screw shaft on the top surface of the helical thread of the female screw. Preferably, it is formed.

Preferably, the nut device is fixed to the grindstone table in a state where it is inserted into a hole opened at the rear end of the grindstone table. This hole also functions as a receiving hole for the tip of the screw shaft that enters the front end of the grinding wheel head beyond the nut device.This configuration shortens the overall length of the grinding wheel head in the retreating direction and achieves a lighter wheel head. Is done. Preferably, the linear guide portion, as described in claim 3, a pair of first guide way for guiding the grinding wheel base in a horizontal direction, and the grinding wheel base is provided between the separation directions of these guide ways. A single second guideway for guiding along one straight line in the horizontal direction. In this case, the screw shaft is disposed so as to have its axis at a position deviated toward the grinding wheel side with respect to the second guideway in a direction orthogonal to the guideways. When a grinding resistance is applied to a grinding wheel fixed to one end of the grinding wheel shaft, the first guideway defines the grinding wheel base via a grinding wheel shaft traversed in a horizontal direction orthogonal to the guideway. A turning moment acts on a horizontal plane. The screw shaft acts on the grindstone head to cancel the moment on the grindstone side with respect to the second guideway, and suppresses yawing of the grindstone head.

The wheel head is preferably arranged concentrically with the wheel shaft to reduce the weight of the wheel head by shortening the rear portion thereof.
Suitable for high-speed feeding. More preferably, the support portion of the grinding wheel shaft on the grinding wheel base utilizes the space between the pair of fluid bearing devices that rotatably supports the grinding wheel shaft as described in claim 5, and the grinding wheel is provided in this space. A built-in motor that rotationally drives the shaft is provided.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes a base of a numerically controlled cam grinder. On this base 1, a horizontal linear guide 2 is provided, and along this guide 2, a grinding wheel head 3 is illustrated. 1 is guided so as to be able to advance and retreat in the left-right direction. The grindstone base 3 has a two-part structure including a grindstone main body 4 that slides on the base 1 and a grindstone shaft support drive unit 5 fixed to the front end of the main body 4 with bolts.

The lower surface of the wheel head body 4 is formed with a keel portion 7 protruding downward therefrom. A pair of guide pressing plates 8 are separated from the lower surface of the keel portion 7 in a horizontal direction perpendicular to the direction in which the main body 4 advances and retreats. It is fixed. The keel portion 7 and a pair of guide holding plates 8 parallel to the keel portion 7
Extend over the entire length in the forward and backward directions. As a result, the pair of guide pressing plates 8 form a pair of U-shaped vertical swing prevention guide grooves 9 on both sides of the keel portion 7 over the entire length of the grindstone base body 4 in the reciprocating direction. On the other hand, a single U-shaped anti-rolling guide groove 10 whose lower part is opened is formed below the center of the keel part 7.

On the base 1, a pair of horizontal guide plates (first guide ways) 11 which are fitted with a predetermined clearance in the pair of pitch prevention guide grooves 9 are fixed, and the roll prevention is performed. A single lateral guide plate (second guide way) 12 that fits in the guide groove 10 with a predetermined clearance is fixed. These guide plates 11 and 12 are long enough to cover the sliding stroke of the wheel head main body 11, and are provided in parallel with each other.

On each lower surface of the grindstone body 4 located on both sides of the keel portion 7, a plurality of static pressure pockets 13 opened on the upper surface of the corresponding horizontal guide plate 11 are arranged along the horizontal guide plate 11. A plurality of static pressure pockets 14 opened on the lower surface of the corresponding horizontal guide plate 11 are also arranged on the upper surface of the pair of guide holding plates 8 along the corresponding horizontal guide plate 11.

Further, a plurality of static pressure pockets 15 which are opened on one corresponding side surface of the lateral guide plate 12 are arranged on each of the inner side surfaces of the pair of guide pressing plates 8 facing each other. ing. Each of the plurality of static pressure pockets 13, 14 and 15 is supplied with a pressurized fluid via an independent unillustrated throttle element. The static pressure of the hydraulic pressure generated in the static pressure pockets 13, 14 and 15 is
The same pressure is set, but if necessary, static pressure pocket 1
5 can be changed from those applied to the static pressure pockets 13 and 14. Alternatively, the static pressure applied to the static pressure pockets 13 and 14 on the grindstone G side can be strongly reduced against the grinding resistance. In order to counter the static pressure, it is also possible to set the static pressure to be higher than the static pressure applied to the static pressure pockets 13 and 14 on the non-grinding stone side.

As a result, the wheel head body 4, that is, the wheel head 3
Is formed by a pair of horizontal guide plates 11, a static pressure pocket 13,
14 is guided in the horizontal direction through the static pressure generated in
Further, it is possible to advance and retreat on the base 1 while being guided by the lateral guide plate 12 along the straight line regulated by the lateral guide plate 12 via the static pressure generated in the static pressure pocket 15.

The grindstone base body 4 is formed with an L-shaped mounting seat 16 for the grindstone shaft support drive unit 5.
The mounting seat 16 includes a horizontal seat for seating the unit 5 in the vertical direction and a vertical wall 1 for seating the unit 5 in the front-back direction.
7 and a vertical seat, which is the front surface of the vehicle. As shown in FIG. 2, the rear portion of the vertical wall 17 has a substantially rectangular parallelepiped box-like structure. A hole 4b is opened in the rear end face of the box-shaped structure portion, that is, the rear end face of the grindstone base 3, and is fixed to the rear end face of the grindstone base 3 with the nut device 20 inserted in the hole 4b.

As shown in detail in FIG. 3, the nut device 20 includes a holding sleeve 21 having a flange portion fixed to the grindstone body 4 by bolts, and a tandem arrangement concentric with an inner hole of the sleeve 21. It is composed of a pair of tightly fitted sleeve-shaped nuts 22F and 22R. These nuts 22F and 22R are provided with flange portions on the side opposite to their facing surfaces, and are fixed to the holding sleeve 21 by bolts at these flange portions.

On the pair of nuts 22F and 22R, female screws 23 are formed concentrically in these inner holes.
3 is screwed with a male screw 25 of a screw shaft 24. According to the present invention, the female screw 23 supports the screw bottom 25b of the male screw 25 in the radial direction with the adjusted hydraulic pressure,
It is configured as a hydrostatic screw supported in the thrust direction by applying adjusted hydraulic pressure to the slopes (flanks) 25f and 25r of the thread.

More specifically, the thread of the external thread 25 is formed as a high-lead trapezoidal external thread having a trapezoidal cross section in the axial direction and a large lead, and the female screw 23 is correspondingly connected to the external thread 25. It is formed as a high-lead trapezoidal female screw that complements the shape of. In order to support the male screw 25 in the radial direction, the top of the thread of the female screw 23 is formed in a flat axial section, and faces the cylindrical screw bottom of the male screw 25 with a predetermined clearance. . A plurality of long-groove-shaped static pressure pockets 26 are formed on the spiral top with a flat cross section of the female screw 23 and are equally arranged in three or four in the circumferential direction. Pressure oil adjusted in pressure is supplied to each of the static pressure pockets 26 via independent throttles 27, and the male screw 25 is driven by the static pressure of the hydraulic pressure generated in these pockets 26 so that the axial center of the pair of nuts 22 </ b> F and 22 </ b> R is formed. Is held.

On the other hand, a pair of nuts 22
In order to support the grinding wheels 3 and F and 22R and the grinding wheel head 3 integral with them in the thrust direction, the nut 22F is provided with a helical thrust statically formed on the flank of the female screw 23 facing the flank 25r on the rear side of the thread of the male screw 25. A pressure pocket 28f is formed, while a spiral thrust static pressure pocket 28r is formed in the nut 22R on the flank of the female screw 23 facing the flank 25f on the front side of the thread of the male screw 25.
Each of the thrust static pressure pockets 28f, 28r is formed by machining one long groove over the entire length of the corresponding nut 22F, 22R, and closing both ends after the machining.

Hydraulic pressure adjusted by independent throttles 29 is supplied to the respective thrust static pressure pockets 28f, 28r, and the static pressure pockets 28f, 28r are supplied to the opposite flank 25f, 25f of the external thread 24 to the male screw 25. The nut device 20 is positioned at a predetermined position according to the screwing position by applying a static pressure outwardly in the axial direction of the nut device 20.

According to the present invention, by constructing the male screw 25 and the nut device 20 to be screwed thereto as described above, the overall length NL of the nut device 20 and the male screw 25 can be changed to the conventional ball nut device and ball screw shaft. And the tandem arrangement of the grinding wheel base 3 and the screw shaft 24 is possible. A hydraulic pressure introducing member 30 is fixed to the rear upper surface of the wheel head main body 4 and receives pressure oil from a hydraulic source (not shown) via a flexible pipe or the like. Holding sleeve 2
1 through the oil passage 31 formed in each of the nuts 22F, 22F.
Pressure oil is supplied to annular grooves 32f, 32r formed on the outer periphery of R. Each of the annular grooves 32f and 32r is provided with the above-described diaphragm 2
The pressurized oil is introduced into the plurality of radial static pressure pockets 26 and one thrust static pressure pocket 28f or 28r through 7, 29.

The pressure oil overflowing from each of the static pressure pockets 26, 28f, and 28r passes through a pair of discharge grooves 25d formed on both sides of the valley of the male screw 25 from the front end of the nut device 20 to the grindstone body. 4 and at the same time, is collected from the rear end of the nut device 20 to an unillustrated oil receiving portion on the base 1, and is returned from the oil receiving portion and the box type space 4s to a hydraulic pressure source. Is done. Reference numeral 34 denotes a nut 22F,
22 shows a recovery passage for guiding pressure oil overflowing from between the opposing surfaces of the 22R to the oil receiving portion.

The box-shaped space 4s in the wheel head main body 4 also functions as a receiving space for the male screw 25 that appears and disappears. The ventilation tool 33 provided on the upper surface of the wheel head main body 4 communicates this space 4s with the atmosphere. The rear end of the screw shaft 24 is the bearing 4
0 is supported on the base 1 while allowing only rotation, and the rear end of the servo motor 41 is fixed to the base 1.
Is connected to the output shaft 42. The rotation axis of the screw shaft 24 is, when viewed in the longitudinal section of FIG.
2 and extends substantially above and preferably
As shown in (2), the distance between the upper surface of the pair of horizontal guide plates 11 or the center between the vertical direction thereof and the axis h2 of the grinding wheel shaft is closer to the axis side of the grinding wheel shaft 50 described later. That is, the vertical interval h1 between the axis of the grinding wheel shaft 50 and the axis of the screw shaft 24 is equal to or less than 1/2 of the interval h2.

The axis of the screw shaft 24 is offset toward the grinding wheel G by a distance Z with respect to the center of the horizontal guide plate 12 when the grinding wheel base 3 is viewed in a plan view as shown in FIG. The screw shaft 24 arranged as described above opposes from right behind the wheel head 3 against the force by which the grinding resistance acting on the wheel G causes the wheel head 3 to retreat backward via the wheel shaft 50. In addition, the grinding force opposes the lateral guide 12 on the same side as the grindstone G against a moment in the direction in which the grinding force tends to turn the grinding wheel base 3 about the lateral guide 12 via the grinding wheel shaft 50, and the grinding resistance is reduced. Strongly against

As shown in FIG. 4, the grindstone shaft support drive unit 5 is formed in a substantially rectangular parallelepiped shape elongated in a direction orthogonal to the feed direction of the grindstone table 3. In this unit 5,
The grindstone shaft 50 is supported rotatably around a horizontal axis perpendicular to the feed direction of the grindstone body 4. In order to support the grindstone shaft 50 so as to be rotatable and unable to move in the axial direction, a pair of bearings 51 and 52 are fixedly disposed at both ends in the unit 5.

Each bearing metal 51, 52 supplies individually regulated pressure oil into a plurality of static pressure pockets 51p, 52p arranged in the circumferential direction of its inner hole, and the grindstone is caused by the static pressure of the hydraulic pressure. The hydrostatic bearing device rotatably supports the shaft 50. A built-in type electric motor 53 is built in between these bearings 51 and 52. The electric motor 53 includes the grinding wheel shaft 5
0, and a rotor 54 fitted in the middle of
And an electromagnetic coil device 55 surrounding the outer periphery of the device.

At one end of the grindstone shaft 50, a grindstone G formed by bonding a segment-shaped CBN (cubic boron nitride) abrasive layer to the outer periphery of a circular base is fixed. A workpiece W (see FIG. 1) such as a camshaft is rotatably supported around a fixed axis in front of the grindstone G by a workpiece supporting device including a headstock and a tailstock (not shown). In accordance with a command from the numerical control device, the spindle motor is rotated by a work drive servomotor (not shown) on the headstock that is controlled synchronously with the grinding wheel feed servomotor 41.

When the grindstone feed servomotor 41 is driven, the screw shaft 24 is rotated, and the nut device 20 screwed to the screw shaft 24 moves along the lead of the high-lead trapezoidal screw as shown in FIG.
, The grindstone table 3 integrated with the nut device 20 is moved forward and backward with respect to the workpiece W along the linear guide mechanism 2. In this case, the grinding resistance acting on the grindstone G by engagement with the workpiece W is such that the grindstone shaft 50, which tends to press the grindstone body 4, in particular, the rear part of the body 4 against the horizontal guide plate 11 of the linear guide mechanism 2. Generates a moment in a plane perpendicular to the axis, but a screw shaft 2
Numeral 4 acts to effectively cancel this moment, and suppresses pitching when the grinding wheel head 3 slides.

The screw shaft 24 disposed closer to the grindstone than the horizontal guide plate 12 acts to effectively suppress the moment when the grindstone head 3 is turned in the horizontal plane. . In the above-described embodiment, the male screw 24 of the screw shaft 24 is formed as a trapezoidal screw, but may be formed as a square screw having a square cross section in the axial direction.

For convenience in manufacturing, the grindstone head 3 is attached to the main body 4.
Although the main unit 4 and the frame of the unit 5 may be integrated with each other. Further, the arrangement of the screw shaft 24, the nut device 20, and the servomotor 41 for relatively rotating the screw shaft 24 and the nut device 20 can take other forms. For example, the screw shaft 24 is fixed on the base 1 so that both the rotation and the axial movement are immovable, and the nut device 20 is supported at the rear of the grindstone main body 4 by allowing only the rotation. Stand body 4
Can be taken to be driven to rotate by the servo motor 41 installed in the camera. Still another form is
5 is projected from the rear of the grinding wheel body 4 with the screw shaft 24
One end of the screw shaft 24 is fixed to the wheel head main body 4, and the screw 2 of the screw shaft 24 is
5 is screwed. In this alternative embodiment, the servo motor 41
Is mounted on the base 1 to rotate the nut device 20.

However, the nut device 20 is not
The illustrated embodiment in which a support mechanism (bearing 40) that is fixed to the rear part and rotationally supports the screw shaft 24 and a drive mechanism (servo motor 41) that rotationally drives the screw mechanism 24 is provided on the base 1, the nut device 20 and the screw By dispersing and disposing the support and drive mechanism of the shaft 24 on the grinding wheel head 4 and the base 1, the mass of the grinding wheel head 3 can be reduced, and the screw shaft 2
4 and the nut device 20 can be simplified to provide them with strong rigidity against stress in the thrust direction, and the screw shaft 24 can be directly driven by the servomotor 41. This is advantageous for the embodiment.

[0037]

As described above in detail, according to the first aspect of the present invention, the screw shaft for feeding the wheel head is disposed in parallel with the linear guide portion immediately behind the wheel head to act on the wheel head. The pitching motion during the sliding motion of the wheel head can be suppressed, and as a result, smooth feed of the wheel head can be realized, Processing accuracy can be improved.

Further, the screw shaft is formed as a high-lead screw, and a radial bearing portion and a thrust bearing portion for applying a static pressure in a radial direction and a thrust direction to the screw shaft are formed in the nut device. The screwing relationship with the nut device is maintained via static hydraulic pressure,
For this reason, the rotational runout and vibration when the screw shaft and the nut device are relatively rotated are attenuated by the hydraulic damping action, and the influence of the runout and vibration on the grinding wheel head is reduced, so that high machining accuracy can be realized.

According to the second aspect of the present invention, the nut device is fixed to the grindstone table while being inserted into the nut storage hole opened in the rear end face of the grindstone table, and the screw shaft screwed to the nut device is connected to the grindstone. The space inside the grindstone table can be used as a space for the screw shaft while taking advantage of the fact that the nut device with a hydrostatic bearing can shorten the overall length compared to the ball screw nut device because it can be retracted into the table. . For this reason, the entire length of the grinding wheel head is shortened and miniaturized, and the entire feeding device of the grinding wheel head can also be reduced in size. In particular, high-speed feeding of the grinding wheel head can be realized.

According to the third aspect of the present invention, a single second guide for guiding the grindstone head along one straight line in the horizontal plane between the pair of first guides for guiding the grindstone head in the horizontal direction. A guide is provided, and the screw shaft is moved in a horizontal direction perpendicular to a feed direction defined by the second guide.
Since it is arranged so as to be deviated more toward the grinding wheel side than the center of the guide, the grinding resistance acting on the grinding wheel can impart a drag on the grinding wheel side to the moment of turning the grinding wheel base in the horizontal plane, Yawing of the wheel head can be suppressed.

According to the fourth aspect of the present invention, a grinding wheel shaft supporting portion which incorporates bearing means for rotatingly supporting the grinding wheel shaft and driving means for rotating the grinding wheel shaft is provided at the front end of the grinding wheel base. A portion of the wheel head behind the support portion can be shortened and downsized, and a wheel head feed mechanism suitable for high-speed feeding of the wheel head is provided. According to the invention as set forth in claim 5, the built-in motor for rotating the grinding wheel shaft is housed in this space by utilizing the space between the pair of fluid bearings supporting the grinding wheel shaft. The entire grinding wheel head including the part can be miniaturized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a wheel head feed mechanism according to the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is an enlarged view of a main part of a hydrostatic screw mechanism used in the embodiment.

FIG. 4 is a plan view of the grindstone feed mechanism shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 Linear guide part 3 Grindstone G grinding stone W Camshaft (workpiece) 4 Grindstone main body 5 Grindstone shaft support drive unit 53 Electric motor 50 Grindstone shaft 4b Hole 11 Horizontal guide plate 12 Horizontal guide plate 20 Nut device 22F, 22R Nut 24 Screw shaft 41 Servo motor 26 Radial static pressure pocket 28f, 28r Thrust static pressure pocket

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Eiji Fukuda Inventor 1-1-1, Asahi-cho, Kariya-shi, Aichi Pref.

Claims (5)

[Claims] 1. A grindstone base rotatably supporting a grindstone via a grindstone shaft guided by a linear guide portion on the base and driven by a motor, and the grindstone stand with respect to a workpiece. A feed screw mechanism provided between the base and the grindstone base for forward and backward feed on the base, the feed screw mechanism including a screw shaft and a nut device engaged with the screw shaft; and any of the screw shaft and the nut device A feed mechanism for a grinding wheel base in a grinding machine comprising a servomotor that rotationally drives one of the screw shafts, when viewed in a plane orthogonal to the linear guide portion, the axis of the screw shaft is greater than that of the linear guide portion. , Arranged in parallel with the linear guide portion, forming the screw shaft as a large screw shaft of a lead,
A radial static pressure bearing portion for supporting the screw bottom of the screw shaft in a radial direction of the screw shaft with a static pressure of hydraulic pressure, and a lead end face of the screw shaft is supported in the axial direction of the screw shaft with a static pressure of hydraulic pressure. A feed mechanism, wherein a thrust hydrostatic bearing portion is formed in the nut device. 2. The wheel head feed mechanism according to claim 1, wherein said screw shaft is rotatably supported on said base, and one end of said screw shaft is connected to said servomotor. A hole is opened and the nut device that engages with the screw shaft is inserted into the hole and fixed, so that the other end of the screw shaft moves back and forth in the hole of the grinding wheel head beyond the nut. A feed mechanism characterized by the following. 3. The wheel head feed mechanism according to claim 1, wherein the wheel is fixed to one end of a wheel shaft rotatable around a horizontal axis orthogonal to a feed direction of the wheel head. A pair of first guideways provided on the base and separated from each other in a direction orthogonal to a feed direction of the grinding wheel head and guiding the grinding wheel head along a predetermined horizontal plane; A single second guideway disposed parallel to the first guideway and between the first guideways to guide the grinding wheel head along one straight line in the predetermined horizontal plane; A feed mechanism wherein the screw shaft is disposed so that its axis is deviated toward the grinding wheel side with respect to the center of the second guideway in the axial direction of the grinding wheel shaft. 4. The wheel head feed mechanism according to claim 2, wherein the wheel head is fixed to the hole that is guided by the linear guide portion so as to be horizontally movable and that is opened at the rear end face. A grindstone head main body, and a grindstone shaft support drive unit incorporating a bearing means fixed to the front end in the feed direction of the grindstone head body for rotatably supporting the grindstone shaft and a grindstone shaft driving means for rotating the grindstone shaft. Feed mechanism characterized by being performed. 5. A wheel head feed mechanism according to claim 4, wherein said bearing means is disposed in said wheel support supporting drive unit in a horizontal direction orthogonal to a feed direction of said wheel head main body. Wherein the grinding wheel shaft driving means is constituted by an electric motor arranged concentrically with the grinding wheel shaft between the pair of fluid bearing devices.