JP2003071710A - Grinding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding machine having a simple structure and achieving high precision machining. SOLUTION: When an elevating/lowering motor 15 rotates a ball screw 16 in either normal or reverse direction, a head 18 is raised or lowered. The head 18 comprises a rotating shaft 23 supported at a rotating shaft holder 25 via a hydrostatic bearing 30. There are provided clearances C1, C2 respectively between both upper and lower ends of the rotating shaft 23 and an end plate 29 and a flange 25a. A workpiece holding body 34 for sucking and holding a workpiece W is secured at a lower end of the rotating shaft 23. Compression air is supplied to the clearances C1, C2 so as to provide thrust to the rotating shaft 23. By adjusting air pressure in the clearances C1, C2, an axial position of the rotary shaft 23 is suitably held and relief pressure for a load is adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinder in which a work or a grindstone is held by a rotary shaft supported by a head and the rotary shaft is rotated to grind the work. It is about.

[0002]

2. Description of the Related Art Conventionally, a grinding machine as shown in FIG. 4 has been known. This grinder has a rotary shaft 72 holding a work W.
Is lowered integrally with the head 73, and the work W is ground by the grinding wheel 74 rotating on the bed.
In this grinder, the descending amount of the head 73 depends on the rotation shaft 7
The amount of decrease is 2, which is almost the same as the actual amount of grinding.

That is, the head 73 moves up and down when the ball screw 81 is rotated by the motor 83. A shaft holder 77 is fixed to the head 73, and the rotary shaft 72 is fixed to the shaft holder 77 by a hydrostatic bearing 85.
Is supported through. The rotational force of the motor 76 is transmitted to the upper end of the rotary shaft 72 via the pulley 75 and the belt 78. The rotating shaft 72 cannot be thrust-moved with respect to the shaft holder 77. A work holder 79 is attached to the lower end of the rotary shaft 72.
Is mounted, and the work W is held therein. On the other hand, a grinding wheel 74 is arranged on the bed and rotated by a motor (not shown).

In such a grinder, the rotary shaft 72 is integrally lowered as the head 73 is lowered. The work W rotates together with the rotating shaft 72, and abuts on the end surface of the rotating grinding wheel 74 to be ground.

On the other hand, there is also a grinding machine in which the rotary shaft 72 is suspended by a spring and is movable in the thrust direction with respect to the head 73. In such a grinder, since the rotary shaft 72 is not fixed to the head 73, when the workpiece W comes into contact with the grinding wheel 74 and grinding is started, the rotary shaft 72 is rotated according to the unevenness of the workpiece W. 72 slightly moves up and down. By this vertical movement, the overload is released by the coil spring.

However, the conventional two types of grinding machines described above have the following problems. That is, in the former surface grinder, since the descending amount of the head 73 coincides with the actual grinding amount, accurate numerical control is possible, but the work W may not escape due to overload and the work W may be damaged. there were.

Although the latter grinder can escape from overload, it cannot move accurately during the grinding because it constantly moves up and down according to the unevenness of the work W.

[0008]

The present invention has been made to solve the above problems. An object of the present invention is to enable accurate numerical control by matching the amount of advance of the rotary shaft with the actual amount of grinding, and when an overload occurs, this is released to prevent damage to the work. It is to provide a grinder capable of doing the above. Another object of the present invention is to provide a grinding machine which can achieve the above-mentioned object with a simple structure and can easily adjust the position of the rotary shaft in the axial direction.

[0009]

In order to achieve the above object, in the invention described in claim 1, a head which is reciprocally moved along one axis by the first driving means, and the head is supported by the head. The second drive means rotates the shaft about its own axis parallel to the one axis, and the third drive means reciprocates along the extending direction of the axis. A support portion provided at an end portion for supporting the work or the rotary grindstone;
The driving means is configured to apply a fluid pressure to the rotating shaft along the axial direction thereof.

Therefore, the position of the rotary shaft in the axial direction can be adjusted by adjusting the fluid pressure by the third drive means. Therefore, the position of the supporting portion can be adjusted, and accurate numerical control can be performed. Moreover, the position of the support can be controlled by adjusting the fluid pressure, and the required grinding pressure can be obtained. Further, when the overload acts in the axial direction of the rotary shaft, the overload can be released by the elastic action of the fluid pressure or the action of the relief valve, and the damage of the work can be prevented in advance. In addition, since the rotary shaft can be moved in the axial direction by adjusting the fluid pressure level, a static pressure bearing or the like for moving the rotary shaft in the axial direction is not required, and the structure is simplified.

According to a second aspect of the present invention, in the first aspect, the head and the rotary shaft are moved up and down along an axis line in a vertical direction, and the supporting portion is provided at a lower end of the rotary shaft. And

Therefore, for example, the work W is applied to the grinding wheel.
It is convenient for a grinding machine having a structure in which the wheels move closer to and away from the upper side. According to a third aspect of the present invention, in the first or second aspect, the third driving means generates a thrust force with respect to the rotating shaft.

Therefore, it is possible to obtain an operation similar to that of the above-mentioned claim 1. According to a fourth aspect of the invention, in the second or third aspect, the third driving means applies a fluid pressure to the rotating shaft from above and below.

Therefore, the thrust force along the axial direction can be appropriately applied to the rotary shaft. According to a fifth aspect of the present invention, in the fourth aspect, the third driving means is provided with a detecting means for detecting a difference in fluid pressures acting above and below the rotation shaft.

Based on the detection result of the detecting means, it is possible to properly maintain the axial position of the rotary shaft, the relief pressure against overload during grinding, and the like.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a grinding machine embodying the present invention will be described below with reference to the drawings of FIGS.

On a bed (not shown), a grinding wheel 12 is rotatably arranged around a vertical axis L. The grinding wheel 12 is rotated in one direction by a motor (not shown).
A column 14 is erected on the bed on the side of the grinding wheel 12. On the upper part of the column 14, a head lifting motor 15 as a first driving means capable of rotating in the forward and reverse directions.
Is provided. A ball screw 16 extending in the vertical direction is connected to the lifting motor 15. A guide rail 17 extending parallel to the ball screw 16 is mounted on the inner surface of the column 14.

The head 18 has a pair of upper and lower nuts 19, and the nuts 19 are screwed into the ball screw 16. Then, when the ball screw 16 is rotated forward or backward by the lifting motor 15, the head 18 is raised or lowered along the guide rail 17.

The head 18 comprises a head main body 21, a rotary shaft holder 25 fixed in the head main body 21, and a rotary shaft 23 supported by the rotary shaft holder 25 via a static pressure bearing 30. . Reference numeral 30a denotes a static pressure pocket of the static pressure bearing 30, and pressure oil is supplied to the static pressure pocket 30a. The axis of the rotary shaft 23 extends in the vertical direction, is rotatable about the axis, and is reciprocable in the direction in which the axis extends, that is, in the vertical direction. A flange 25a is formed at the lower end of the rotary shaft holder 25 so as to project inward. An end plate 29 is fixed to the upper end of the rotary shaft holder 25, and the end plate 29 has an insertion hole 29a through which the small diameter portion 23a of the rotary shaft 23 is inserted.
Is transparently installed. The upper and lower ends of the rotary shaft 23 and the end plate 29
And the clearance C with the flange 25a, respectively.
1, C2 are provided.

A cylindrical bracket 28 having a lid is fixed to the upper end surface of the head body 21, and a support hole 28a is provided at the center of the bracket 28. A pulley 38 is rotatably supported in the support hole 28a via a bearing. An extension portion 23b at the upper end of the rotary shaft 23 is connected to a center hole 38a of the pulley 38 via a key 39 so as to be slidable only in the axial direction. As shown in FIG. 2, a belt 42 is wound around the pulley 38 on the output shaft 40a of the motor 40 as the second driving means and the pulley 38. Therefore, by the motor 40, the belt 42, the pulley 38, the key 39, the extension portion 23
The rotating shaft 23 is rotated in one direction via b.

A work holder 34 as a support is fixed to the lower end of the rotary shaft 23, and the work W is sucked and held on the lower surface thereof by vacuum suction. As shown in FIG. 3, a plurality of air passages 50 and 51 are formed through the end plate 29 and the flange 25a so as to open toward the upper and lower end surfaces of the rotary shaft 23. These air passages 50 and 51 are connected to the air supply source 60 via pressure control valves 53 and 54, respectively, and the clearances C1 and C2 between the end plate 29 and the flange 25a and the upper and lower end surfaces of the rotary shaft 23 are provided. It is designed to supply pressurized air to. Thrust (force in the thrust direction) is applied to the rotary shaft 23 by the pressurized air.

Both the clearances C1 and C2 and the valve 5
Pressure sensors 55 and 56 as detecting means are connected to the air passages 50 and 51, respectively. Then, the openings of the pressure adjusting valves 53 and 54 are adjusted based on the pressure detection signals from the pressure sensors 55 and 56, and the pressures in the clearances C1 and C2 are adjusted. Therefore, the pressure acting in the thrust direction of the rotary shaft 23 is adjusted. Reference numeral 61 denotes a pipe passage 61 between the air supply source 60 and the air passages 50 and 51. Further, in this embodiment, the air supply source 60, the pressure control valves 53 and 54, the pipe line 61 and the like constitute a third drive means.

Next, the operation of the grinding machine configured as described above will be described. First, the head W is at the upper original position (the position where the work W does not contact the grinding wheel 12), and the work W is sucked and held by the work holder 34 with the motor 40 stopped. Next, the grindstone 12 is rotated and the work W is rotated by the motor 40,
Thus, when the head 18 is lowered, the grinding wheel 12 starts grinding the work W. Further, during the grinding process, the air pressure in the clearances C1 and C2 is adjusted by adjusting the opening degree of the pressure adjusting valves 53 and 54,
While properly maintaining the axial position of the rotary shaft 23,
Adjust the relief pressure for the load.

Therefore, by advancing or retracting the head 18, it is possible to secure a grinding amount according to the advancing amount and the retracting amount, and it is possible to perform high-precision machining by appropriately numerically controlling the elevation position of the work W.

When an overload acts on the work W during this machining, the rotary shaft 23 moves against the pressure in the clearances C1 and C2, and the overload is released.
The work W is prevented from being damaged.

Therefore, the following effects can be obtained in this embodiment. Basically, the advancing amount of the head 18 becomes the grinding amount of the work W, so that grinding can be performed under accurate numerical control.

When the unevenness of the work W is large and the rotary shaft 23 receives a large reaction force during grinding, the rotary shaft 23 retracts. Therefore, although basically quantitative grinding is performed,
When the load is excessive, the load can be escaped, so that the work W can be prevented from being damaged while performing the quantitative grinding.

When accurate grinding is required such as finish grinding, the pressure in the clearances C1 and C2 is increased to perform quantitative grinding, and when not so accurate grinding such as rough cutting In this case, the pressure in the clearances C1 and C2 can be lowered to perform grinding. Therefore, as described above, it is possible to perform high-precision grinding, prevent work damage, and perform various kinds of grinding freely according to the purpose of use.

(4) In the structure in which the rotary shaft 23 is moved up and down together with the rotary shaft holder 25, a hydrostatic bearing or the like is required between the rotary shaft holder 25 and a member supporting the rotary shaft holder 25. , The configuration becomes complicated. In particular,
If the position of the rotary shaft 23 in the axial direction is detected and the position is used for control, it becomes more complicated. Further, since the hydrostatic bearing is required to have high accuracy, it becomes difficult to process it. On the other hand, in this embodiment, the clearance C
1, C2 are provided and the rotary shaft 23 is moved up and down, the configuration is simple and the processing is not difficult.

The present invention is not limited to the above embodiment, but can be embodied in the following modes. In the above-described embodiment, the head 18 and the rotary shaft 23 are configured to be movable up and down along the vertical axis, but are configured to be reciprocally moved along the horizontal axis.

In the above-described embodiment, the work W is attached to the lower end of the rotary shaft 23.
The work W is mounted on the bed (not shown) side.

Embodying the invention in a grinder that uses loose abrasive grains. Therefore, the grinding wheel becomes unnecessary, and, for example, loose abrasive grains are scattered on the turntable, and the work is brought into contact with the turntable.

In the above-described embodiment, the pressure in the pipeline 61 is detected to detect the pressure in the clearances C1 and C2. On the other hand, the pressure acting on the rotary shaft 23 in the axial direction thereof should be detected by a sensor such as a load cell that contacts the rotary shaft 23.

The load acting on the rotary shaft 23 is detected by the pressure sensors 55, 56, and the replacement of the grinding wheel 12 and the dress-up time are determined. That is,
When the pressure sensors 55 and 56 detect a pressure higher than a set value, an indicator for displaying the pressure should be provided. That is, when the degree of wear of the grinding wheel 12 is large, the sharpness of the grinding wheel 12 becomes poor and the pressure contact force between the grinding wheel 12 and the workpiece W becomes large. Therefore, the detection value of the upper pressure sensor 55 becomes high, and the detection value of the lower pressure sensor 56 becomes low.

Providing detection means for detecting the axial position of the rotary shaft 23. For this purpose, a pressure sensor such as the pressure sensors 55 and 56 for detecting the back pressure of the clearances C1 and C2, or a non-contact sensor such as a capacitance sensor is used. Rotating shaft 2
By detecting the position of the shaft 3 in the axial direction, it is possible to control the vertical position of the rotary shaft 23, that is, the work W.

[0036]

As described above in the embodiment, in the present invention, by making the amount of advance of the rotary shaft and the actual amount of grinding coincide with each other, accurate numerical control is possible, and
When an overload occurs, it can be released to prevent damage to the work. Therefore, it is possible to perform high-precision machining and prevent damage to the work piece in advance. Further, in the present invention, the above-mentioned effects can be achieved with a simple configuration.

[Brief description of drawings]

FIG. 1 is a sectional view of a surface grinder of an embodiment embodying the present invention.

FIG. 2 is a partial side view of the same.

FIG. 3 is an explanatory diagram showing a configuration of an air circuit.

FIG. 4 is a sectional view showing a conventional grinding machine.

[Explanation of symbols]

15 ... Head lifting motor as first driving means, 18
... head, 23 ... rotary shaft, 40 ... motor as second drive means, 53 ... pressure control valve as third drive means, 54 ... pressure control valve as third drive means, 5
5 ... Pressure sensor as detecting means, 56 ... Pressure sensor as detecting means, 60 ... Air supply source as third driving means, 61 ... Pipe line as third driving means.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Itazu             1333 Azabe, Mugikawa-cho, Mugi-gun, Gifu Prefecture             Nagase Integrex Co., Ltd. F term (reference) 3C034 AA08 BB07 CA16 CB01 CB18                 3C043 BA03 BA15 CC04 DD05

Claims (5)

[Claims] 1. A head which is reciprocally moved along an axis by a first driving means, and a head which is supported by the head and is rotated about its own axis parallel to the one axis by a second driving means. And a rotation shaft reciprocally moved by the third driving means along the direction in which the axis extends, and a support portion provided at an end of the rotation shaft for supporting the work or the rotary grindstone. A grinding machine characterized in that the driving means of No. 3 makes a fluid pressure act on the rotary shaft along the axial direction thereof. 2. The grinding machine according to claim 1, wherein the head and the rotary shaft are moved up and down along a vertical axis line, and the support portion is provided at a lower end of the rotary shaft. 3. The grinding machine according to claim 1 or 2, wherein the third driving means generates a thrust force with respect to a rotating shaft. 4. The grinding machine according to claim 2, wherein the third driving means applies a fluid pressure to the rotating shaft from above and below the rotating shaft. 5. The grinding machine according to claim 4, wherein the third driving means includes a detecting means for detecting a difference in fluid pressure acting on the upper and lower sides of the rotary shaft.