JPS6339765A - Method and device for dressing grinding stone - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to the reshaping of a grinding wheel, and this reshaping involves shaping the outer peripheral surface of the grinding wheel to make it a perfect circle. This means giving the outer peripheral surface an accurate cross-sectional profile with the desired surface support.

The process of making a grinding wheel completely circular is generally called "rounding," and the process of imparting the required surface support to the outer periphery of the grinding wheel is generally called "correction."

The present invention is particularly applied to the reshaping of so-called "super Y-resistant" grinding wheels, as will be described later, but it can also be used for reshaping ordinary grinding wheels.

Contoured grinding wheels are used for precise shaping of various types of rotating mechanical parts, such as engine camshafts. As a grinding wheel that has been refurbished to perform a specific action is worn during its use, abrasives and metal particles that have worn away during its working life are removed from the outer circumferential surface of the grinding wheel and this outer circumferential surface is precisely Both eyes often require retouching to restore the correct cross-sectional contour.

Grinding wheels are generally manufactured by bonding abrasive grains or particles with a binder and forming them into a disk shape. Typical abrasives are aluminum oxide and silicon carbide. Various binding materials are used, such as synthetic resins, metals, or melt-solidified materials.

It is clear that the outer circumferential surface of the dressing wheel must be formed of an abrasive material that is capable of cutting or tIF polishing the hard surface of the grinding wheel without causing excessive wear itself. Thus, dressing wheels typically consist of diamond particles embedded in a hard matrix such as nickel, tungsten carbide, or other hard matrix.

In some applications, it is becoming increasingly common to use ultra-wear-resistant grinding wheels using, for example, diamond or cubic boron nitride as an abrasive in a fused bond. Many problems arise when modifying such grinding wheels using conventional methods. If the profile of the grinding wheel is flat, i.e. if the outer peripheral surface of the grinding wheel is completely cylindrical, it is possible to rotate both wheels in engagement with each other while moving their engagement surfaces axially relative to each other. Appropriate modification of the outer circumferential surface of the grinding wheel is carried out by. In that case, by varying the relative lateral feed rate as well as the forces between the wheels and the relative rotational speeds of the wheels, the surface properties of the grinding wheel and its modification conditions can be varied. However, if the grinding wheel is required to have a non-cylindrical profile, a relative lateral movement is not possible and the shaping of the grinding wheel profile is carried out by a crushing action or a rotating dressing action of the dressing wheel. Although such a method can achieve the necessary rounding and shaping of the grinding wheel, it is difficult to control the modification of the outer peripheral surface of the grinding wheel in a scheduled manner.

[Object and effect of the invention]

The present invention provides a novel method and apparatus for refinishing a grinding wheel by providing other parameters that are varied to vary the modification conditions of the outer circumferential surface of the grinding wheel.

According to one aspect of the invention, the step of rotating a grinding wheel about its axis at a predetermined speed, and rotating a reshaping wheel having a hard peripherally formed surface with a cross-sectional profile complementary to said desired cross-sectional profile about a parallel axis. and a step of causing a relative movement between the reshaping wheel and the grinding wheel in the Mn direction with respect to their rotation axes to press the outer peripheral surface of the reshaping wheel against the outer peripheral surface of the grinding wheel. , maintaining the pressing engagement; and controlling the rotational speed of the dressing wheel to create a speed difference between the engaging outer peripheral surface of the dressing wheel and the grinding wheel. A method is provided for reshaping a grinding wheel to form a peripheral surface of a desired cross-sectional profile. Preferably, the dressing wheel is controlled such that its peripheral speed is lower than the peripheral speed of the grinding wheel.

It has been discovered that when using this method, the conditions for modifying the outer circumferential surface of the grinding wheel can be varied by adjusting the rotational speed of the reshaping wheel to vary the speed difference between the engagement surfaces of both wheels. Therefore, by setting the rotational speed of the dressing wheel to an appropriate speed for a specific composition of the grinding wheel and polishing wheel, the outer circumferential surface characteristics of the finished grinding wheel can be planned. In addition to the normal action on the outer circumferential surface of the grinding wheel, the effect of this difference in speed on the outer circumferential surface is
Rotation by the outer circumferential surface of the dressing wheel causes a "wearing effect". It is this abrasive effect that determines the outer surface characteristics of the finished wheel, and the extent of this effect is dependent on the specific rotational speed of the dressing wheel.

As mentioned above, the present invention is particularly directed to an ultra-wear resistant wheel in which the grinding wheel is made of cubic titanide or diamond embedded in a melt-solidified bonding wheel, and in which at least the outer circumferential surface of the reshaping wheel is Applications include diamond particles embedded in a binder such as nickel or tungsten carbide.

The rotational speed of the dressing wheel can be controlled by driving the dressing wheel with a variable speed servo motor. In this case, the rotational speed of the servo motor is continuously controlled to maintain the rotational speed of the dressing wheel at a substantially constant predetermined value. Alternatively, the rotational speed of the servo motor and thus the dressing wheel can be varied periodically.

In another embodiment of the present invention, the rotational speed of the dressing wheel is controlled by applying a braking load to the dressing wheel when the rotational speed of the dressing wheel is greater than a predetermined value; The size is variable and determined to reduce the rotational speed of the dressing wheel to the predetermined value.

As is well known, by feeding one wheel at a constant speed toward the other wheel, a crimping engagement between the outer circumferential surfaces of the grinding wheel and the dressing wheel is maintained. However, according to another feature of the invention, if the rotational speed of the dressing wheel is below the predetermined value, feeding is carried out at the first speed, and if the rotational speed of the dressing wheel is above the predetermined value, The feed rate is controlled in accordance with the rotational speed of the dressing wheel so that the second speed is lower than this. In this way, before the wheels are brought into engagement with each other, the rotational speed of the dressing wheels is at or below a predetermined value, so that the wheels are fed relatively quickly in the mutual direction. However, as soon as the wheels engage each other, the grinding wheel accelerates the dressing wheel above a predetermined rotational speed, so that
The feed rate is switched to a lower value suitable for the wheels in active engagement.

The present invention also provides means for rotating the grinding wheel around its axis at a predetermined speed, means for rotating the reshaping wheel around parallel axes, and a means for rotating the grinding wheel around its axis at a predetermined speed, and a means for rotating the reshaping wheel around a parallel axis, and a means for rotating the grinding wheel around its axis at a predetermined speed. means for effecting a relative movement of the wheels; means for detecting the rotational speed of the resizing wheel; and a control means for controlling the grinding wheel to return to the original value.

If the speed of rotation of the dressing wheel is controlled by the braking means, the means for rotating the dressing wheel about its axis:
It includes a rotating shaft having means for coaxially mounting a dressing wheel, and braking means act on said rotating shaft or on a part that rotates with said rotating shaft. For example, the braking means includes a disc brake mechanism, the disc of which is mounted on the shaft of rotation or a part that rotates therewith.

The braking mechanism is pneumatically actuated, in which case the control means
It includes an air control valve that controls the supply of compressed air to the brake mechanism.

The control means includes a differential control device for comparing the speed sensor signal with preset data indicative of the predetermined speed and operating the air control valve to reduce the difference between the signal and the data.

Preferably the pneumatic control valve is solenoid operated and actuated by an electrical signal from the differential control.

Means for rotating the dressing wheel about its axis includes a motor drivingly connected to a rotating shaft to which the dressing wheel is mounted. In this case, the differential control device is connected to the motor and turns off the motor when the rotational speed of the dressing wheel rises above the predetermined value.

(Example) Hereinafter, an example of the present invention shown in the drawings will be described in detail.

In FIG. 1, a dressing wheel 1 is attached to the end of the rotating shaft 11.
0 is mounted, and this reshaping wheel is driven by a servo motor 12 via a suitable connection.

The grinding wheel 14 to be reconditioned is mounted on a rotating shaft 15 driven by a motor 16. The dressing wheel 10 and the grinding wheel 14 are freely rotatable about parallel axes, and the assembly including the Q cutting wheel and its motor is such that the dressing wheel 10 and the grinding wheel 14 are rotatable about parallel axes, and the assembly including the Q cutting wheel and its motor is configured so that the dressing wheel 10 and the grinding wheel 14 can be rotated in a direction perpendicular to the axis of rotation of both wheels. It is installed so that it is sent towards the wheel.

This feeding mechanism is of an electric type and can be of any known type, so it will not be described further.

A speed sensor 17 is arranged adjacent to the outer circumference of the reshaping wheel 10, this sensor is connected to a differential control device 18,
A sensor sends a signal to this control device indicating the rotational speed of the dressing wheel. A rotation counter 19 is connected to the control device to display the rotation speed. The differential control device 18 is connected to the servo motor 12 that drives the dressing wheel 10 and is configured to maintain the rotational speed of the dressing wheel at a predetermined value. This predetermined value is adjustable and is preset in the differential control device 18. Alternatively, the differential controller can be programmed to periodically vary the rotational speed of the dressing wheel.

This structure automatically activates the servo motor 12 when it is detected by a device that compares the signal from the speed sensor 17 with a preset value that the rotational speed of the resizing wheel 10 deviates from a preset value in the differential controller. The rotational speed of the dressing wheel is controlled to return to a preset value. Since the servo motor and control system operating in this manner are readily available, the control system will not be described further.

In operation, motors 12 and 16 are first switched on. The dressing wheel 10 then rotates at a predetermined speed preset in the differential control device without being subjected to any external load. This can be, for example, 750 rpm. The grinding wheel 14 can rotate at a rotational speed of 1000 rpm, for example.

At the same time as the dressing wheel and grinding wheel are rotated,
The grinding wheel 14 is fed towards the dressing wheel 10 until both wheels come into contact.

When in contact, the grinding wheel] 4 increases the rotational speed of the dressing wheel 10 to more than 750 rpm (the diameter ratio of these wheels is such that the rotational speed of the dressing wheel 10 increases when the dressing wheel is freely rotated by the grinding wheel). Approximately 3000
(can be set to be equal to or higher than rpa+). However, the rotational speed of the reshaping wheel or the predetermined 75 Orpm
As soon as the differential controller 18 responds,
Decrease the speed of the servo motor and therefore the speed of the dressing wheel.

Speed sensor 17 can be of any suitable construction. For example, the sensor can be activated by optical sensing of an axial encoder or by optical sensing of the outer circumference of the wheel using a stroboscope. Alternatively, the sensor may use one or more transducers, such as accelerometers, piezoelectric strain gauges, or transducers, which generate a signal that varies depending on the rotational speed of the dressing wheel.

In addition, the differential control device has a rotational speed of 75
As soon as 0 rpal or more -L is reached, the feed speed of the grinding wheel toward the reshaping wheel is controlled to be reduced from the initial indexing speed to a lower operating speed.

Alternatively or additionally, the feed rate of the grinding wheel can be controlled by the position of the rotation axes of the grinding wheel and the dressing wheel. In this case, the feed rate is reduced when the axes of both wheels reach a position where the outer peripheries of both wheels come into contact with each other. The relative position of the wheels' axes of rotation can be controlled, for example, by optical gratings, linear voltage differential transformers (LVDs)
T), capacitive transducers, inductosyn transducers, etc. can be used for detection. The signals of such devices are used to control the feed rate of the grinding wheel, reducing the feed rate when a predetermined relative position of both wheels is reached.

During continuous operation, the grinding wheel 14 is always connected to the reshaping wheel 10.
However, the servo motor 12 is controlled to always maintain the preset speed.

As the grinding wheel 14 is fed towards the dressing wheel 10, the dressing wheel 10 applies a crushing/dressing action to the outer periphery of the grinding wheel, making it "perfectly round", i.e., making it perfectly round. The grinding wheel is shaped into a circular shape, and the contour of the outer circumferential surface of the grinding wheel is shaped according to the contour of the outer circumferential surface of the dressing wheel.

However, at the same time, the lower limit outer circumferential speed of the dressing wheel causes an abrasion effect between the outer peripheral surface of the dressing wheel and the outer peripheral surface of the grinding wheel pressed against it.

The surface properties of the grinding wheel caused by this combined crush-wear effect vary depending on the degree of the abrasion effect, which abrasion effect is dependent on the rotational speed of the dressing wheel. Therefore, for a certain type of grinding wheel, for a certain type of straightening wheel, and for a certain rotational speed of the straightening wheel,
By adjusting the rotational speed of this dressing wheel to a preset rotational speed or by periodically varying this rotational speed, it is possible to plan for variations in the surface properties of the finished grinding wheel.

Therefore, in the normal method, the outer peripheral surface contour of the grinding wheel and/or
Or, even if it is impossible to schedule adjustment of the outer peripheral surface due to the material, this can be done.

In another embodiment shown in FIG. 2, the rotational speed of the grinding wheel 10 is controlled by a braking mechanism 13 connected between the motor 12 and the shaft 11 of the dressing wheel, and is not directly controlled by the motor 12. It's not about doing it. Identical components of both these structures are designated by identical reference numerals.

In the structure of FIG. 2, the differential control device 18 is also connected to the motor 12 that drives the dressing wheel 10, and turns off the motor 12 when the rotational speed of the dressing wheel reaches or exceeds a predetermined value. As before, this predetermined value is adjustable and can be preset in the differential controller.

However, the embodiment of FIG. 2 controls a solenoid actuated air control valve 20 which controls the amount of air supplied from the air source through regulator 22 to manifold 23. This manifold 23 distributes air to a plurality of air-operated brakes in the link-brake system 13 which are connected to the drive motor of the dressing wheel. The air actuated brakes can be of any number, but are shown schematically at 24.

In this structure, the differential controller detects that the rotational speed of the resizing wheel 10 is greater than a preset value in the differential controller by comparing the signal from the speed sensor 17 with a preset value. When the air control valve 20
is actuated to actuate the brake 24, thereby slowing down the dressing wheel 10.

In operation of this machine, the motors 12 and 16 are first switched on.The dressing wheel 10 then rotates at a predetermined speed preset in the differential control device without any external load. The grinding wheel 14 can be rotated at a rotational speed of 11000 rpm as in the previous embodiment.

At the same time as the dressing wheel and grinding wheel are rotated,
The grinding wheel 14 is fed towards the dressing wheel until both wheels come into contact. When in contact, the grinding wheel 14 increases the rotational speed of the dressing wheel 10 to 75 Orpm.
Increase above. However, as soon as the rotational speed of the dressing wheel exceeds the predetermined 750 rpHI, the differential control 18 responds by turning off the motor 12, activating the valve 20, and activating the air brake 24 to reduce the braking load. Add to the reshaping wheel.

Also, as in the previous embodiment, the differential control device:
As soon as the rotational speed of the dressing wheel exceeds 750 rpm, the feed speed of the grinding wheel toward the dressing wheel is controlled to decrease from the initial indexing speed to a lower operating speed. Also, as in the previous embodiment, the feed rate of the grinding wheel can be controlled by the positions of the rotational axes of the grinding wheel and the dressing wheel.

During continuous operation, the grinding wheel 14 is always connected to the reshaping wheel 10.
Attempting to rotate at a speed higher than the rated speed of 750 rpm,
Also, a braking force is constantly applied to the dressing wheel to reduce its rotational speed. The braking force is controlled to increase in response to excess speed of the dressing wheel.

The braking action of the trimming wheel and the hunting action of the trimming wheel, which is constantly braked toward the rotational speed set by precertification, are carried out between the outer circumferential surface of the trimming wheel and the outer circumferential surface of the grinding wheel that is pressed by it. causes the aforementioned abrasive effects. Thus, for a particular type of dressing wheel and grinding wheel, variations in the surface characteristics of the dressing wheel can be anticipated by adjusting the preset rotational speed of the dressing wheel.

FIG. 3 shows the drive of the dressing wheel of the embodiment of FIG.
Details of a typical structure of a braking device are shown.

Referring to FIG.
The other end of this shaft is attached to the casing 27.
It is rotatably mounted in bearings 25 and 26 inside.

The end of the shaft 11 opposite the dressing wheel 10 is connected to the output shaft of the motor 12 by a coupling 28. Adjacent to coupling device 28 and mounted on shaft 11 is a disc plate assembly of a pneumatic disc brake mechanism. One of the air actuated brake pad mechanisms for a disc brake is shown at 30, with a suitable number of brake pad assemblies disposed along the circumference of the disc.

This brake mechanism is of a commercially available type, and a number of brake band assemblies can be selected depending on the required braking force. As mentioned above, this brake mechanism is preferably of a type in which the braking torque is proportional to the operating air pressure.

[Brief explanation of drawings]

1 is a schematic illustration of a first embodiment of the device according to the invention; FIG.
The figure is a schematic representation of a second embodiment of the device according to the invention;
This is a cross-sectional view of the part of the device shown in the figure that drives and brakes the reshaping wheel. 10... Reshaping wheel, 12... Servo motor, 13... Connection-υj movement device, 14... Grinding wheel,
16...Motor, 18...Differential control device, 20...
- Air control valve, 22... Regulator, 23... Manifold, 24... Brake, 30... Brake pad. Applicant's agent Sato-Yu I3 1

Claims (1)

[Claims] 1. Rotating a grinding wheel around its axis at a predetermined speed, and rotating a reshaping wheel having a hard outer circumference forming surface with a cross-sectional contour that complements the desired cross-sectional contour around a parallel axis. producing a relative movement between the reshaping wheel and the grinding wheel in a direction perpendicular to their rotation axes to press the outer peripheral surface of the reshaping wheel against the outer peripheral surface of the grinding wheel; a method of reshaping a grinding wheel to form a peripheral surface of a desired cross-sectional profile on a grinding wheel, the method comprising the step of maintaining a pressing engagement of the reshaping wheel and the engaging peripheral surface of the grinding wheel. A method for reshaping a grinding wheel, comprising the step of controlling the rotational speed of a reshaping wheel to produce a difference. 2. The method according to claim 1, characterized in that the rotational speed of the dressing wheel is controlled so that the peripheral speed of the dressing wheel is lower than the peripheral speed of the grinding wheel. 3. A method according to claim 1 or 2, characterized in that at least the outer peripheral surface of the dressing wheel contains diamond particles embedded in a binder. 4. A method according to claim 3, characterized in that the binder is selected from nickel and tungsten carbide. 5. The rotation speed of the face-up wheel is controlled by a speed-controlled servo.
5. A method according to any one of claims 1 to 4, characterized in that the method is controlled by driving a dressing wheel by a motor. 6. The rotational speed of the servo motor is continuously controlled to maintain the rotational speed of the dressing wheel at a substantially constant predetermined value.
Method by section. 7. A method according to claim 6, characterized in that the rotational speed of the servo motor and thus of the dressing wheel is varied periodically. 8. When the rotational speed of the dressing wheel is greater than a predetermined value, the rotational speed of the dressing wheel is controlled by applying a braking load to the dressing wheel, and the magnitude of the braking load is variable, 5. A method according to any one of claims 1 to 4, characterized in that the rotational speed of the reshaping wheel is determined to be reduced to the predetermined value. 9. By sending one wheel toward the other wheel at a constant speed, the crimping engagement between the grinding wheel and the outer periphery of the dressing wheel is maintained, and when the rotational speed of the dressing wheel is below the predetermined value, The feed speed is adjusted to correspond to the rotation speed of the reshaping wheel so that when the rotation speed of the reshaping wheel is higher than the predetermined value, the feed is performed at the first speed, and the feed is performed at a second speed lower than the predetermined value. 9. A method according to any one of claims 1 to 8, characterized in that the method comprises controlling. 10. The crimping engagement between the outer peripheries of the grinding wheel and the dressing wheel is maintained by feeding one wheel toward the other at a predetermined speed, and the feeding is stopped while both wheels are close to a predetermined relative position. occurs at a first speed, and after the wheels have reached said predetermined relative position, a second, lower speed occurs.
10. A method according to any one of claims 1 to 9, characterized in that the feed rate is controlled in response to the relative position of the rotation axes of the grinding wheel and the dressing wheel, as occurs in the speed. 11. means for rotating the grinding wheel at a predetermined speed about its axis; means for rotating the reshaping wheel about parallel axes; a grinding wheel recalibration device comprising: means for performing relative movement; and a means for detecting the rotational speed of the recalibration wheel, the rotational speed of the recalibration wheel being adjusted from a predetermined value in response to a signal from the detection means. A grinding wheel reconditioning device characterized by comprising a control means for controlling the grinding wheel to return to the predetermined value when the grinding wheel is removed. 12. The rotating means for rotating the reshaping wheel about its axis includes a rotating shaft having means for coaxially attaching the reshaping wheel, and a braking means acts on a portion rotating together with the rotary shaft. Apparatus according to claim 11. 13. Device according to claim 12, characterized in that the braking means include a disc brake mechanism, the disc of which is mounted on the rotating shaft. 14. Device according to claim 13, characterized in that the braking mechanism is pneumatically actuated and the control means includes an air control valve for controlling the supply of compressed air to the braking mechanism. 15. The control means further comprises a differential control device for comparing the speed sensor signal with preset data indicative of the desired predetermined speed and operating the air control valve to reduce the difference between the signal and the data. Device according to claim 14, characterized in that it comprises: 16. Apparatus according to claim 14, characterized in that the air control valve is solenoid operated and actuated by an electrical signal from the actuation control device. 17. The means for rotating the reshaping wheel about its axis includes a motor drivingly connected to a rotating shaft on which the reshaping wheel is mounted, and the differential control device is connected to the motor and rotates the reshaping wheel. 16. The device according to claim 15, wherein the motor is turned off when the rotational speed rises above the predetermined value.