JPH1158193A - Surface grinding method and surface grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out grinding with a high accuracy in a partial and harrow region, in a plane grinding device for carrying out grinding on an end surface of a grinding wheel. SOLUTION: An eccentric bearing 37 is arranged on a tip end part of a cylindrical shaft 23 capable of rotating through a belt transmission means 34 by a revolutionary driving device. A grinding wheel shaft 25 is rotatably arranged on the eccentric bearing 37, and a grinding wheel 28 is arranged on the tip of the grinding wheel shaft 25. The grinding wheel shaft 25 is rotatably connected to a self rotation driving device 27 by a connecting shaft 26 provided with a constant velocity universal joint 45. Grinding is carried out while simultaneously performing self rotation and revolution by the grinding wheel 28. Self rotation speed is reduced, and revolution speed is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface grinding method and a surface grinding apparatus, and more particularly, to a technique for grinding, for example, a valve seat surface of a valve seat. In this specification, “surface grinding” is processing using a grindstone, and covers a wide range from grinding at a rough finish level to a so-called polishing level such as super-finishing.

[0002]

2. Description of the Related Art Conventionally, as this type of surface grinding apparatus, for example, one described in Japanese Patent Application Laid-Open No. 60-191750 is known. This surface grinding device processes a work while rotating and revolving a grindstone. As a reference, “Latest Machine Construction”, pages 275-277, issued by Yokendo Co., Ltd. on February 20, 1977, has a planetary motion mechanism as an example of an apparatus used for internal grinding. Is described. This inner surface grinder also rotates and revolves the grinding wheel.

[0003]

When a valve seat is used as a workpiece, it is difficult to machine the valve seat surface with a conventional surface grinding device. That is, since the valve seat is a deformed product, it is not appropriate to rotate the valve seat about the center of the valve seat surface as a rotation center due to the occurrence of eccentric load and difficulty in chucking. Therefore, the valve seat is ground and the valve seat surface is ground.

[0004] However, the above-mentioned surface grinding apparatus has a relatively large revolving radius of the grindstone, and performs the processing with a high rotation speed and a low revolving speed, whereas the valve seat surface of the valve seat is partially formed. This is because it is narrow and narrow within the recess. Further, in the valve seat, it is necessary to provide a high sealing property to the valve seat surface. Therefore, it is optimal to provide a concentric processing pattern. In some cases, a processed pattern having the shape of a circle occurs, and the sealing performance cannot be improved.

On the other hand, in the conventional inner surface grinding apparatus, since the grinding wheel is processed in the outer peripheral side surface while the grinding wheel is fed in the axial direction, it is needless to say that the valve seat surface of the valve seat cannot be processed. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a surface grinding method and a surface grinding apparatus capable of easily and satisfactorily grinding even when a deformed object such as a valve seat is used as a work. Aim.

[0006]

According to the present invention, the following technical measures have been taken in order to achieve the above object. That is, in the surface grinding method according to the present invention, the grindstone is rotated and revolved, and when grinding a predetermined portion of the surface of the work in a stationary state at the end face of the grindstone, the revolution number of the work relative to the work is calculated based on the rotation number. Is also higher. According to such a method, the main action of the processing can be caused by the revolution of the grindstone, the revolution radius of which is relatively small, and a partial and narrow portion such as the valve seat surface of the valve seat. It is possible to make it suitable for processing.

When the rotation speed is set so that the rotation speed of the grindstone is substantially zero when viewed from the stationary workpiece, a concentric machining pattern can be obtained. Therefore, it is suitable when the sealing performance is improved on the valve seat surface of the valve seat. Grinding stone is fed by fluid pressure,
If the feed is stopped by a stopper that resists the fluid pressure and a method of automatically controlling the position of the stopper is adopted, the processing feed of the grindstone can be performed accurately and reliably. Therefore, it becomes suitable for high-precision processing such as super finishing.

On the other hand, in the surface grinding apparatus according to the present invention, there is provided a surface grinding apparatus having a head capable of mounting a grindstone.
In the head, a cylindrical shaft having an inner diameter eccentric portion is rotatably supported, and a revolving drive device that rotationally drives the cylindrical shaft is provided.A whetstone shaft is rotatably supported by the eccentric portion, The head is provided with a rotation driving device that rotationally drives the grinding wheel shaft, and the rotation driving device and the grinding wheel shaft are connected via a universal joint.

With such a structure in which the rotation driving device and the grinding wheel shaft are connected by the universal joint, not only the revolution driving device but also the rotation driving device can be fixed. Therefore, it is possible to increase the speed of the revolution of the grindstone, and to simplify the structure and prevent a failure. A grindstone feeder is provided for bringing the grindstone shaft closer to the work, and the grindstone feeder makes the grindstone contact the work by fluid pressure. The grindstone feeder is provided with a stopper control device for preventing the movement of the grindstone shaft against the fluid pressure, and the stopper control device can automatically control the position of the stopper.

[0010] With this configuration, it is possible to accurately and reliably feed the processing of the grindstone, which is suitable for high-precision processing such as super finishing.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 is a plan view schematically showing an example of the grinding process, and includes a loading (work set) station 1, a rough finishing station 2, a finishing station 3, a post (inspection) station 4, and an unloading (work unloading). The stations 5 are arranged in a circular shape, and a circular swivel table 6 is intermittently rotated at a central portion thereof. The surface grinding device 8 according to the present invention is installed in, for example, the rough finishing station 2 and the finishing station 3 among them.

In this embodiment, a flat valve seat as shown in FIG. 7A is used as a work W, and an annular valve seat provided on the opening edge of the valve port 10 or the like in the work W. The surface of the surface 11 is ground, or the surface of the end surface 11 of the deformed pipe as shown in FIG. 7B is ground so that concentric polishing lines are formed. FIG. 2 is an overall side view of the surface grinding device 8 according to the present invention.
Is a device body 14 having a bed 12 and a column 13
A saddle 17 provided on the column 13 of the apparatus main body 14 so as to be able to move up and down by a large stroke by a main elevating device 16, and a sub-elevating device 18
19 that can be moved up and down with a small stroke
And

The above-mentioned swivel table 6 can pass horizontally above the bed 12 with respect to the surface grinding device 8. First, the head 19 will be described. The head 19 includes a cylindrical shaft 23 rotatably held with its axis centered in the vertical direction with respect to the head base frame 22, a revolving drive 24 for rotating the cylindrical shaft 23, and a cylindrical hole of the cylindrical shaft 23. A grindstone shaft 25 rotatably held inside, and this grindstone shaft 25,
A rotation driving device 27 that is driven to rotate via an intermediate connecting shaft 26
And Then, the grinding wheel 2 is placed in front of the grinding wheel shaft 25.
8 are provided.

As shown in FIG. 1, the head base frame 22 is provided with a box-shaped bracket 30 in which a bearing case 29 is provided, and the cylindrical shaft 23 is provided with upper and lower bearings provided inside the bearing case 29. 31 and 32, it is rotatably held around the rotation center P. That is, the rotation center P becomes the revolving axis. A drive input wheel 33 such as a timing pulley is provided on the upper part of the cylindrical shaft 23, and the revolving drive device 24 (see FIG. 2) is connected to the drive input wheel 33 via a transmission member 34 such as a timing belt. Is transmitted to the cylindrical shaft 23.

In the cylindrical shaft 23, the inner diameter of the portion holding the grinding wheel shaft 25 in the cylindrical hole is an eccentric portion 36 eccentric with respect to the rotation axis P of the cylindrical shaft 23.
Further, an eccentric bearing 37 is inserted. The grinding wheel shaft 25
Is rotatably held around a rotation center Q by upper and lower bearings 38 and 39 provided inside the eccentric bearing 37. That is, the rotation center Q becomes the rotation axis.

Therefore, when the cylinder shaft 23 is rotated,
The rotation axis Q for rotation of the grinding wheel shaft 25 is the rotation center P for revolution.
It will move around the circumference. As shown in FIG. 3, an arc-shaped long hole 41 is provided at a lower end surface of the eccentric bearing 37 at a portion where the fixing bolt 40 is inserted into the bearing case 29. Bearing 3
An angle display scale 42 is provided so as to surround 7.

Therefore, by loosening the bolt 40, the eccentric bearing 37 can be rotated within the range of the elongated hole 41, thereby adjusting the amount of eccentricity between the rotation center P for revolution and the rotation center Q for rotation. Can be. Further, once the bolts 40 are removed, the amount of rotation of the eccentric bearing 37 can be increased according to the pitch width of the elongated holes 41. Accordingly, the amount of eccentricity adjustment beyond the range of the elongated holes 41 can be adjusted. Also becomes possible.

The upper and lower bearings 31 and 32 and the eccentric bearing 37 provided inside the bearing case 29 (see FIG. 1).
The upper and lower bearings 38 and 39 provided in the inside are formed by mist-like lubricant supplied to passages 43 and 44 provided in the respective peripheral walls of the bearing case 29, the cylindrical shaft 23, the eccentric bearing 37 and the like. , Lubricated and cooled. The revolution drive device 24 and the rotation drive device 27 (see FIG. 2) are fixed to the head base frame 22. Each of these uses an electric motor or a fluid pressure motor having a speed reducer and capable of variable speed control.

As described above, not only the revolution driving device 24,
Since the rotation drive device 27 is also fixed to the head base frame 22, the intermediate connection shaft 26 connecting the grinding wheel shaft 25 and the rotation drive device 27 has a universal joint 45 (see FIG. 1) at at least one end. There are things. In the present embodiment, the input side (that is, the rotation drive device 27 side) is a universal joint 45, and the output side (that is, the grindstone shaft 25 side) is an elastic coupling 46. As the universal joint 45, a constant velocity ball joint was used. Note that a constant velocity ball joint 45 may be used instead of the elastic coupling 46 to absorb changes in the axial direction and the radial direction. Further, non-constant velocity universal joints may be provided at both ends of the intermediate connection shaft 26 so that the final output is rotated at a constant speed.

Next, the main lifting device 16 (see FIG. 2) will be described. The main elevating device 16 is such that the saddle 17 can be moved up and down with a large stroke with respect to the column 13 of the device main body 14 as described above, and the structure is commonly employed in conventionally known vertical machine tools and the like. For example, a fluid pressure cylinder and a screw feed mechanism are used in the same manner as the lifting device.

Next, the sub lifting device 18 will be described. The sub-elevating device 18 has a grindstone feeding device 48 and a stopper control device 49. As shown in FIGS. 3 and 4, the grindstone feeding device 48 includes a pair of guide bars 52 erected and held vertically between the upper and lower support pieces 17 a and 17 b of the saddle 17, and the guide bars 52 are vertically movable. Lift 53 held by the upper part and the upper support piece 17a of the saddle 17
, A suspension shaft 54 suspended in a parallel manner at an intermediate portion between the two guide bars 52, a cylinder driving portion 55 formed around a lower end portion of the suspension shaft 54 in the elevator 53, and an upper portion of the cylinder driving portion 55. And a micro-lift drive unit 56 provided in the control unit.

The box-shaped bracket 30 and the head base frame 22 (that is, the entire head 19) are fixedly connected to the elevating table 53. The cylinder drive unit 55 is configured to move the plunger 58 shorter than the length of the cylinder hole 53a formed in the lift 53 to the suspension shaft 54.
Of the cylinder bore 53
A fluid such as air can be selectively pressurized and supplied into the cylinder hole 53a through upper and lower fluid passages 62 and 63 communicating toward inner sides of the lids 60 and 61 that close the upper and lower portions of the cylinder a. Things.

That is, the cylinder driving section 55 is a so-called double-acting cylinder in which the plunger 58 is fixed and the cylinder hole 53a, that is, the lift 53, moves up and down. The lifting table 5 by the cylinder driving unit 55
3, the downward drive, that is, downward pressurization by fluid pressure,
The grindstone 28 at the tip of the grindstone shaft 25 is brought into contact with the work W held on the swivel table 6 (see FIG. 2).

The micro-lift drive unit 56 includes a suspension shaft 54
A downward tapered member 65 fixed to an intermediate portion of the outer cylindrical body, an outer cylindrical body 66 fixed to the elevating table 53 so as to surround the downward tapered member 65, and a downward tapered member 65
A collet 68 having a wedge piece 67 that can be inserted into a circumferential gap between the collet 68 and the outer cylindrical body 66; a spring 69 for urging the collet 68 away from the downward tapered member 65;
And a fluid such as air to the lower surface of the collet 68 through the inside of the suspension shaft 54 and the fluid passages 71 and 72 provided in the midsole support 70. It can be supplied under pressure.

The wedge piece 67 of the collet 68 is formed between the slits in a cylindrical member around the suspension shaft 54 by forming axial slits at a plurality of locations in the circumferential direction. Therefore, it has elasticity that can expand and contract in the radial direction. That is, the microlift drive unit 56
By supplying the fluid to the fluid passages 71 and 72, the collet 68 is raised, and the wedge piece 67 is pressed into the circumferential gap between the downward tapered member 65 and the outer cylindrical body 66.
And the suspension shaft 54 can be locked in an indirectly immobile state.

Therefore, for example, if the plunger 58 is positioned at the neutral position in the longitudinal direction of the cylinder hole 53a in the cylinder driving section 55 and the microlift driving section 56 is in the above-mentioned locked state, the main lifting device 16 , The elevator 53 can be held in a stable state, thus enabling such usage. On the other hand, as shown in FIG.
The contact piece 75 provided at an appropriate position on the side and the contact piece 7
It has a stopper 76 provided so as to interfere with contact when the 5 is lowered by a predetermined amount, and a position control unit 77 which enables the stopper 76 to move up and down. The stopper 76 and the position control unit 77 may be provided for the saddle 17, but are preferably provided at appropriate positions on the apparatus body 14 side for space reasons.

The position control unit 77 drives the feed screw mechanism 79 to rotate by a drive unit 78 such as a motor with a speed reducer.
With this, the holding table 80 of the stopper 76 is raised and lowered, and the stop position of the stopper 76 can be changed and adjusted appropriately and with high precision from a small stroke to a large stroke corresponding to the lifting and lowering of the saddle 17 by the main lifting device 16. I have.

The drive unit 78 takes into account the amount of elevation of the saddle 17 with respect to the apparatus body 14, and stores in advance data such as the average amount of wear of the grindstone 28 by one grinding operation, or one operation. Depending on the remaining amount of the grindstone 28 measured each time of grinding or an artificial input, a stopper 76 is provided for each grinding.
Is controlled by NC so as to decrease by a predetermined amount. That is, the stopper control device 49 includes the cylinder driving unit 5
5 (see FIG. 4), when the lift 53 (the grindstone shaft 25 and the grindstone 28) is lowered in fluid pressure, the contact piece 75 on the lift 53 and the stopper 76 on the apparatus body 14 are brought into contact with each other, The lowering of the elevator 53 is prevented at a highly accurate position against the pressure.

That is, the stopper 76 controls the descending position of the grindstone 28 and also controls the descending speed of the grindstone 28. In this stopper control device 49, the descent data (corresponding to the descent data of the lower end level of the hoisting table 53 and the whetstone 28) obtained by lowering the stopper 76 in one grinding operation is obtained by the post station on the downstream side after the grinding. 4 (see FIG. 6), the data is collated with the measurement data obtained at the time of inspection, and is fed back to the rough finishing station 2 or the finishing station 3 as a correction control value for the pass / fail or error.

Although not shown, when the wear amount of the grindstone 28 reaches the use limit, in order to detect this, the lower limit of the lift 53 is provided between the lift 53 and the saddle 17. There are provided a proximity switch and various sensors for detecting the state. The surface grinding device 8 (see FIG. 2) having such a configuration is disposed in the rough finishing station 2 and the finishing station 3 as shown in FIG. 6, and an annular valve seat for the workpiece W shown in FIG. A specific example of processing the surface of No. 11 will be described.

In the rough finishing station 2, the outer diameter of the annular valve seat 11 is 7 mm, the outer diameter of the grinding wheel is 8 mm, the inner diameter of the grinding wheel is 5 mm, and the eccentric amount of the revolution axis P and the rotation axis Q is 4 mm.
3 (revolution axis) is set to +500 rpm, and the grinding wheel axis 2
The rotation speed of No. 5 (rotation axis) was set to -4000 rpm. still,
The rotation number +-means that the rotation direction is normal or reverse.

In the finishing station 3, two-stage finishing is performed. In the first stage, the rotation speed of the cylindrical shaft 23 is increased by +500.
rpm, and the number of revolutions of the grindstone shaft 25 was set to +4000 rpm. In the final finishing stage, the rotation speed of the cylindrical shaft 23 is increased to +2500.
rpm, and the rotation speed of the grinding wheel shaft 25 was set to +2500 rpm. In the final finishing stage, the rotation of the grindstone shaft 25 with respect to the workpiece W becomes zero, and concentric grinding lines are formed on the surface of the annular valve seat 11.

When roughing and finishing are continuously performed in one station without being divided into a roughing station and a finishing station, the rotational speed of the cylindrical shaft 23 is increased by +5 in roughing.
00 rpm, and the rotation speed of the grinding wheel shaft 25 is +4000 rpm
m, and in the finish, the rotational speed of the cylindrical shaft 23 is +250.
0 rpm, and the rotation speed of the grinding wheel shaft 25 is +2500 rpm
And

By the way, if only a concentric grinding line is to be obtained, the grinding wheel may be fixed at the eccentric position of the cylindrical shaft 23. However, when the grindstone is fixed, the contact position between the grindstone and the work becomes constant, causing uneven wear of the grindstone. However, by making the grindstone shaft rotatable as a rotation shaft as in the present invention, uneven wear can be prevented. Note that the present invention is not limited to the above embodiment.

For example, in the grindstone feeding device 48 of the sub-elevating device 18, the fluid pressure used is air, but it can be replaced with hydraulic pressure or water pressure. Wheel axis 25
By applying a vibration to the structure, it is possible to perform grinding at a so-called polishing level such as super finishing. In addition, the shape, structure, drive method, and the like of the members over the details of each part can be appropriately changed to conventionally known ones.

The work W is not limited to a valve seat or the like, but may be anything other than a nozzle seal surface or any other object for grinding a flat portion. Needless to say, it is not limited to a deformed product or a flat product. Further, the material is not particularly limited.

[0037]

As is apparent from the above description, in the surface grinding method according to the present invention, the grinding wheel is rotated and revolved at a speed higher than the rotation speed (as viewed from the workpiece), and the stationary workpiece is removed. Since it is ground, it is suitable for processing a partial and narrow portion. When the grinding wheel does not rotate when viewed from the workpiece, a concentric processing pattern can be obtained,
This is suitable when the sealing performance is improved on the valve seat surface of the valve seat.

If the processing of the grinding stone is stopped by a stopper and the stopper is automatically controlled and positioned, it can be suitable for high-precision processing such as super finishing. On the other hand, in the surface grinding device according to the present invention, a grinding wheel shaft is provided in an eccentric portion of an inner diameter of a cylindrical shaft that is rotationally driven by a revolution driving device, and the grinding wheel shaft is rotationally driven by a rotation driving device via a universal joint. Therefore, the rotation driving device can be fixed, and the revolution speed of the grindstone can be increased.

If a stopper control device is provided for the grindstone feeder for bringing the grindstone into contact with the workpiece by fluid pressure and preventing the grindstone from being fed against the fluid pressure, it is suitable for high-precision machining such as super finishing. Can be something.

[Brief description of the drawings]

FIG. 1 is an enlarged side sectional view showing a part (head) of FIG. 2;

FIG. 2 is an overall side view schematically showing a surface grinding apparatus according to the present invention.

FIG. 3 is a bottom view corresponding to FIG. 4;

FIG. 4 is an enlarged side sectional view showing a part (grinding wheel feeding device) of FIG. 2;

FIG. 5 is a plan view showing a state of grinding a workpiece.

FIG. 6 is a plan view schematically showing an example of a grinding process in which the surface grinding apparatus of the present invention is implemented.

FIG. 7 is a perspective view showing an example of a work.

[Explanation of symbols]

 2 Rough finishing station 3 Finishing station 6 Rotating table 8 Surface grinding device 12 Bed 13 Column 14 Main body 19 Head 23 Cylindrical shaft 24 Revolution driving device 25 Grinding wheel shaft 27 Rotation driving device 28 Grinding stone 36 Eccentric part 45 Universal joint 48 Grinding stone feeding device 49 Stopper control device 76 Stopper W Work

Claims (5)

[Claims] 1. A surface grinding method for rotating and revolving a grindstone (28) to grind a predetermined portion of a surface of a work (W) in a stationary state at an end face of the grindstone (28), wherein the work (W) Wherein the revolution speed is higher than the revolution speed. 2. The surface grinding method according to claim 1, wherein the rotation speed is set such that the rotation speed of the grindstone (28) is substantially zero when viewed from the stationary work (W). Surface grinding method. 3. The surface grinding method according to claim 1, wherein the machining feed of the grinding wheel (28) is performed by a fluid pressure, and the feed is stopped by a stopper (76) that resists the fluid pressure. 76) A surface grinding method characterized by automatically controlling the position of 76). 4. A head (1) capable of being equipped with a grindstone (28).
9) In the surface grinding apparatus having the configuration (9), a cylindrical shaft (23) having an inner diameter eccentric portion (36) is rotatably supported by the head (19), and a revolving shaft that rotationally drives the cylindrical shaft (23). A driving device (24) is provided. A grinding wheel shaft (25) is rotatably supported by the eccentric portion (36), and a grinding wheel shaft (2) is mounted on the head (19).
5) a rotation drive device (27) for rotating the drive is provided;
The surface grinding device characterized in that the rotation driving device (27) and the grinding wheel shaft (25) are connected via a universal joint (45). 5. A grindstone feeder (48) for bringing the grindstone shaft (25) closer to the work (W) is provided, and the grindstone feeder (48) moves the grindstone (28) by fluid pressure to the work (W). W), and a stopper control device (49) for preventing movement of the grinding wheel shaft (25) against the fluid pressure is provided, and the stopper control device (49) is provided with a stopper The surface grinding apparatus according to claim 4, wherein the position of (76) can be automatically controlled.