JPH09267258A - Lapping machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase dynamic rigidity by arranging a thrust bearing, whose thrust force acting direction is opposite to a sliding thrust bearing and which restricts a rising quantity of a lower lap plate within a prescribed range, on a rotary shaft of the lower lap plate. SOLUTION: A dynamic pressure thrust bearing 19 is arranged between it and a driving body 9 in a lower part of a base stand 7, and the driving body 9 receives upward applying thrust by a dynamic pressure thrust bearing 8 of an upper part, and a position is fixed so that the driving body 9 does not float, and a vertical position of a lower lap plate 2 is made immovable. Upper and lower surfaces of a work 6 are lapped in a desired mirror surface shape by mutually rubbing action by the upper and lower lap plates 1 and 2. Therefore, these lap work surfaces 1a and 2a always maintain a flat condition, and the work 6 is lapped with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lapping machine having a lower lapping plate supported by a dynamic thrust bearing.

[0002]

2. Description of the Related Art Conventionally, as a lapping machine for supporting a lower lapping plate by a dynamic pressure thrust bearing, Japanese Patent Publication No. 61-5454.
There is one described in No. 4. The dynamic thrust bearing in this lapping machine consists of a combination of a ring-shaped upper bearing race and a lower bearing race, and the lower bearing race has an annular groove in which the upper bearing race is diametrically oriented. It is fitted while maintaining the clearance.
The groove is filled with lubricating oil, and the lower surface of the upper bearing race is alternately carved with tapered portions and flat portions, and the upper bearing race rotates to form a peripheral portion between the lower bearing race and the lower bearing race. When a relative speed in the direction is generated, dynamic pressure is generated in the taper portion of the lower surface of the upper bearing race due to the relative flow velocity generated between the upper bearing race and the liquid, giving an upward levitation force to the upper bearing race, and Counter the weight. In this way, the dynamic thrust bearing differs from the rolling bearing consisting of balls and rollers in that the upper and lower parts rotate with a liquid film inside and outside of 10 microns, so the vibration generated externally is transmitted to the lower bearing race side. Is a liquid film that prevents it from being transmitted to the upper bearing race. As a result, there is an advantage that the smooth operation of the lower lap plate is guaranteed, the accuracy of the lapping work is improved, and the number of accidents such as cracking of the workpiece is reduced. Furthermore, since the metals do not come into direct contact with each other at the bearing,
There is no fear of wear or baking, and the life is semi-permanent.

[0003]

However, in the lapping machine using the above-mentioned dynamic thrust bearing, the level of the upper bearing race changes in units of micron as the number of revolutions and the load change. In other words, in the dynamic thrust bearing, the upper bearing race has dropped to the level of the bottom surface because no dynamic pressure is generated when it stops, but when rotation starts, dynamic pressure proportional to the number of revolutions is generated and an oil film is formed. The bearing race rises and stabilizes at a level commensurate with the load applied to the lower lap plate. However, if the rotational speed and the load fluctuate midway, the thickness of the oil film changes and the level of the lower lap plate changes in units of microns. FIG. 2 is a conceptual diagram showing the relationship between the load and the rotational speed of the lower lap plate and the flying height. However, in reality, machining is not performed at different rotation speeds and loads each time, but is continuously performed under almost the same rotation and load conditions, so the actual flying height is almost the same, but the flying height changes. Is preferably as small as possible in order to maintain the accuracy of processing work.

By the way, these lapping machines are generally provided with a device called a sizing device for automatically controlling the thickness of an object to be polished. This is a device that constantly measures the thickness of the object to be lapped that is sandwiched between the upper and lower lap plates and terminates the lap processing when the thickness that decreases as the lap reaches a predetermined value. In this sizing device, in order to measure the thickness of the object to be polished, the level of the lower lap plate supporting the object to be polished or the level of the upper lap plate in a state of being in close contact with the lower lap plate is used as the origin. Therefore, as shown in FIG. 2, the level of the reference lower lap plate changes due to the fluctuation of the load and the rotation speed, and therefore the measured value of the thickness of the object to be polished changes. However, in reality, as described in the previous section, processing is almost always performed under the same load and rotational speed, and the measured values of the sizing device are performed while correcting these fluctuations. Although it is possible to solve the management problem, if the fluctuation value is small, the frequency of correction will be reduced and the advantages in machining work will be increased. Therefore, technical innovation in that direction is required.

[0005]

In order to solve the above-mentioned problems, the present invention is directed to a sliding thrust bearing (hereinafter referred to as a dynamic pressure thrust bearing) which utilizes as a thrust direction bearing force the dynamic pressure self-induced in the lubricating oil by rotation. The rotation axis of the upper lap plate is supported in the thrust direction, and the object to be polished held in the carrier is sandwiched by the upper and lower lap plates, and then the upper and lower lap plates are rotated around the vertical axis. In a lapping machine that laps while rotating relative to itself and revolving and rotating the carrier about a vertical axis, the action direction of thrust is opposite to the sliding bearing that supports the load of the lower lap plate and the amount of lower lap plate rise is specified. A thrust bearing that limits the range is installed on the rotary shaft of the lower lap plate.
As a result, as the lapping machine is activated and the rotational speed increases, dynamic pressure is generated between the upper and lower race surfaces of the sliding bearing that supports the load of the lower lap plate, and the dynamic pressure pushes up the race surface. Then, the rotation axis of the lower lap plate starts to rise. Here, if the vertical load is small or the rotation speed is too fast, the upper race surface tries to rise further,
At the same time, the dynamic pressure of the other slide thrust bearing operates in the opposite direction, and its magnitude and fluctuation amount correspond to the same load and rotation speed, so thrust forces are competing against each other, and the rotation axis of the lower lap plate rises. It is limited and the level of the lower lap plate is kept within a predetermined range. Also, this state is so-called initial thrust load (preload) between opposing bearings in order to enhance the dynamic rigidity of the rotating shaft supported by ordinary rolling bearings.
Although it is often the same as that, it is a dynamic pressure thrust bearing with high dynamic rigidity originally, but the rigidity of the rotating shaft system is further increased, and the vibration damping and stability of rotation are improved. .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a lapping machine to which the present invention is applied will be described below with reference to the drawings. FIG. 1 is a sectional view of a lapping machine according to the present invention. First, this lapping machine is generally called a double-sided lapping machine, and has a pair of upper and lower lapping plates 1 and 2, a sun gear 3, an internal gear 4, for example, four carriers 5, and a carrier 5 Are arranged around the sun gear 3 at approximately 90 degrees, and each of these carriers 5
Is meshed with both the sun gear 3 and the internal gear 4 by a gear 5a formed on the outer periphery thereof. A plurality of workpieces (hereinafter, referred to as works) 6 are usually held on each carrier 5, and these works 6 are placed on the lower lap plate 2 and on these works 6. The upper lap plate 1 is pressed under a predetermined pressure.

On the other hand, this lapping machine is constituted by a so-called 4-way drive system, in which the lower lapping plate 2, the sun gear 3 and the internal gear 4 are rotationally driven in the same direction at a predetermined speed, and the upper lapping plate is also used. 1 is rotationally driven in the opposite direction to the above at a predetermined speed. As a result, the carrier 5 revolves around its own axis, the work 6 rotates in opposite directions, and the lower lap plates 1 and 2 perform an eccentric motion (trochoid).
The upper and lower surfaces of the work 6 are configured to be lapped into a predetermined mirror surface by the co-sliding action.

Next, details of this lapping machine will be described. First, 7 is a fixed base, and a lower lap plate driving body 9 is rotatably supported on the base 7 by an annular fluid bearing 8. An internal gear driving body 10 is rotatably supported on the outside of the base 7. Furthermore, in the central part of the base 7, there is an inner-outer triple shaft 1 that vertically penetrates them.
1, 12 and 13 are provided so as to be rotatable relative to each other. The driving body 9 is fixed to the outer shaft 13 with a key. The lower lap plate 2 is horizontally mounted on the upper portion of the driving body 9 in a detachable manner, and is engaged with a plurality of driving pins 15 projecting from the upper portion of the driving body 9. .

The internal gear 4 is horizontally fixed to the upper portion of the driving body 10. Further, the sun gear 3
Is fixed to the upper end of the intermediate shaft 12. A rotary head 14 for driving the upper lap plate 1 is fixed to the upper end of the center shaft 11. Further, the rotational driving force is transmitted to the center shaft 11 by the motor and the power transmission gear device provided in the lower portion (not shown) of the machine. As a result, the upper lap plate 1 is rotationally driven at a predetermined speed via the center shaft 11, the rotary head 14, and the engaging head 18. In addition, the sun gear 3 is connected via the intermediate shaft 12 to, for example, the upper lap plate 1 described above.
It is rotationally driven at a predetermined speed in the opposite direction.

Further, the lower lap plate 2 is rotationally driven at a predetermined speed in the same direction as the sun gear 3, for example, via the outer shaft 13 and the driving body 9. Furthermore, the internal gear 4 is rotationally driven at a predetermined speed, for example, in the same direction as described above via the drive body 10. At this time, however, since the driving body 9 is rotatably supported on the base 7 via the dynamic pressure thrust bearing 8, and the lower lap plate 2 is driven to rotate by the driving body 9, its rotation Sometimes, the lower lap plate 2 does not generate any vibration or surface wobbling. Therefore, the lower lap plate 2 and the upper lap plate 1 placed on the upper part rotate stably with high accuracy in a state where no vibration or surface wobbling occurs. Further, another dynamic pressure thrust bearing 19 is provided between the lower part of the base 7 and the driving body 9, and the driving body 9 receives the thrust force upwardly received by the upper dynamic pressure thrust bearing 8, The position is fixed so that the driver 9 does not float.

By the above rotary drive, the carrier 5 is revolved while rotating, and the work 6 is rotated by the upper and lower lap plates 1, 2.
A predetermined eccentric movement is performed between the two, and the upper and lower surfaces of the work 6 are lapped into a desired mirror surface by the sliding action of the upper and lower lap plates 1 and 2. Since no vibration or surface wobbling occurs on the upper and lower lap plates 1 and 2 at all, no wavy irregularities are generated on these lap work surfaces 1a and 2a, and the lap work surface 1
a and 2a always maintain a flat state, and the work 6 is lapped with high precision.

On the other hand, the probe 16 of the sizing device which is vertically suspended from the upper part of the upper lap plate support 17 which moves up and down together with the upper lap plate 1 has a rotary head in which the contactor of the tip end is fixed in the vertical direction. It is in contact with the upper center of 14 while being pressed from above. The probe 16 has the capability of detecting the vertical movement of the contact in units of 0.1 micron, and can accurately measure the vertical movement amount of the upper lap plate 1. Therefore, the fluctuation in the vertical position of the upper lap plate 1 placed on the work 6 is the amount of decrease in the thickness of the work 6 that gradually decreases due to the lapping action, and therefore the output of the measurement from the probe or If a value corresponding to the desired thickness is set in advance and the machine is stopped at that point, the work 6 will be automatically lapped at the planned thickness.

However, in order for this operation to be performed accurately, it is premised that the upper and lower positions of the lower lap plate 2 are immovable, and if this position fluctuates, the work 6
The correlation between the thickness and the measurement value by the probe 16 will be lost. In the present invention, as described above, the lower lap plate driving body 9 is provided with the dynamic pressure thrust bearings 8 and 19 on the upper and lower sides to restrain the fluctuation of the vertical position, so that the influence on the measurement value of the probe 16 is minimized. It is possible to stop at. In the embodiment, the lower lap plate driving body 9
Although the dynamic pressure thrust bearing 19 is provided in order to suppress the rise of the above, it is also possible to incorporate a rolling bearing composed of balls or rollers in place of the dynamic pressure thrust bearing 19.

[0014]

As described above, according to the present invention, the lower thrust plate is supported by the sliding thrust bearing which utilizes the dynamic pressure self-induced in the lubricating oil by the rotation of the load of the lower lap plate as the thrust direction bearing force. By installing a thrust bearing in which the acting direction of the thrust force is opposite to that of the dynamic pressure thrust bearing on the rotary shaft of the lap plate, the vertical load of the lower lap plate is reduced, and even if the rotation speed increases, The amount of rise is limited within a predetermined range, the measured value of the thickness of the object to be polished is stabilized, and the accuracy of the thickness management by the sizing device is improved and the labor is reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a load, a rotation speed, and a flying height in a conventional example.

[Explanation of symbols]

 1 Upper Wrap Plate 1a Upper Wrap Work Surface 2 Lower Wrap Plate 2a Lower Wrap Work Surface 3 Sun Gear 4 Internal Gear 5 Carrier 6 Work 7 Base 8 Dynamic Pressure Thrust Bearing (Upper) 9 Lower Wrap Plate Driver 10 Internal Gear Driver 11 Medium shaft 12 Intermediate shaft 13 Outer shaft 14 Rotating head 15 Driving pin 16 Probe 17 Upper lap plate support 18 Engaging head 19 Dynamic thrust bearing (lower)

Claims (2)

[Claims] 1. A rotating shaft of a lower lap plate is axially supported by a sliding thrust bearing (hereinafter abbreviated as a dynamic pressure thrust bearing) that utilizes a dynamic pressure self-induced in lubricating oil as a thrust bearing force by rotation. , After sandwiching the object to be polished held in the carrier by the upper and lower lap plates, both the upper and lower lap plates are relatively rotated about the vertical axis,
In a lapping machine that polishes a carrier while revolving and rotating about a vertical axis, a thrust bearing that has a thrust force acting direction opposite to that of the sliding thrust bearing and limits the amount of rise of the lower lapping plate within a predetermined range is a lower lapping plate. A lapping machine characterized by being installed on the rotating shaft of. 2. A sliding thrust bearing that uses dynamic pressure self-induced in the lubricating oil by rotation as thrust bearing force is used as the thrust bearing for limiting the rise of the lower lap plate. Lap board.