JPH0255194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for accurately truing each grinding surface of an angular type grinding wheel.

[Prior art]

In recent years, so-called CBN grinding wheels that use hard materials such as cubic boron nitride as abrasive grains have come into use. CBN grinding wheels are extremely expensive, so when truing the grinding surface,
It is necessary to keep the depth of cut of the truing tool to the minimum necessary to remove the waviness of the grinding wheel, and to extend the life of the grinding wheel as long as possible. On the other hand, if the depth of cut is too small, the waviness of the grinding surface cannot be completely removed, resulting in a problem that the grinding accuracy is adversely affected. Therefore, in such a grinding wheel truing device, it is necessary to limit the depth of cut of the truing tool with an accuracy of about ± several μm. However, in reality, the grinding wheel thermally expands due to changes in air temperature, bearing temperature, etc., and the position of the grinding surface changes. Furthermore, the grinding wheel causes minute wear due to grinding, and the degree of this wear is not always constant. Therefore, in order to cut with the cutting depth of the truing tool with the above-mentioned precision, it is necessary to cut to a constant thickness based on the grinding surface of the grinding wheel before truing. For this purpose, it is necessary to accurately measure the position of the ground surface before truing, and for this purpose, a contact sensor is used to detect the position of the ground surface,
A method of grinding to a constant thickness from this ground surface is used.

However, in the case of a so-called angular type grinding wheel that has two grinding surfaces that are inclined with respect to the normal direction of the grinding wheel, a single contactor is attached to the grinding surface in the normal direction of the grinding wheel. Even if the position of the grinding surface is detected by contacting the grinding surface with , it is not possible to accurately determine the positions of both sides of the grinding surface. Therefore, the truing device used in the conventional cylindrical grinding wheel cannot accurately truing the grinding wheel into a predetermined angular shape.

[Purpose of the invention]

SUMMARY OF THE INVENTION The present invention has been made in order to improve these conventional drawbacks, and provides a new truing device that can truing both grinding surfaces of an angular type grinding wheel with high precision and uniform thickness. With the goal.

[Structure and operation of the invention]

FIG. 1 is a block diagram showing the concept of the present invention.

That is, the present invention includes: a truing tool 2 that performs truing by grinding the grinding surface of a grinding wheel; a truing tool drive device 4 that can move the truing tool in the normal direction and axial direction of the grinding wheel; Contactor 6 that can come into contact with each grinding surface of the grinding wheel
A contact drive device 8 that can move the contact at least in the normal direction of the grinding wheel; A contact detection sensor 10 that is connected to the contact and detects contact by its vibration or the like; and the contact detection sensor. the contactor drive device is operated from its movement start point until it is detected that the contactor has contacted each grinding surface of the grinding wheel, and the amount of movement of the contactor is detected. a contactor movement amount detection unit 12; a storage unit 14 that operates the contactor movement amount detection unit immediately before and after truing and stores each detected movement amount; a displacement detection unit 16 that detects the displacement of each grinding surface of the grinding wheel immediately before truing with respect to each grinding surface of the grinding wheel immediately after the previous truing, from the movement amount detected immediately after the previous truing and the movement amount detected immediately after the previous truing; , Correcting the operating trajectory of the truing tool during the previous truing relative to the grinding surface of the grinding wheel immediately before truing, based on the displacement of each grinding surface of the grinding wheel detected by the displacement detection section. A truing control unit 18 that controls the truing tool drive device so that each grinding surface of the grinding wheel immediately before truing is trued to the same thickness.
The present invention relates to a truing device for an angular type grinding wheel consisting of the following.

Here, the angular type grinding wheel refers to a grinding wheel that has two or more grinding surfaces that grind by line contact, and those grinding surfaces are inclined with respect to the normal direction of the grinding wheel.

The contactor 6 can be moved in the normal direction of the grinding wheel 20 by a contactor drive device 8 . That is,
Inputting the control signal of the contact movement amount detection unit 12,
The contactor drive device 8 can move the contactor 6 in the normal direction from the origin of the drive device until it comes into contact with the grinding wheel 20 . Determination as to whether the tip of the contact has contacted the grinding wheel 20 is based on a signal output from the contact detection sensor 10. The contact detection signal from the contact detection sensor 10 is transmitted to the contact movement amount detection unit 1.
2, the contact movement amount detection unit 12 sends a signal to the contact drive device 8 to stop the movement of the contact, and outputs the movement amount of the contact to the storage unit 14. , the storage unit 14 stores the value.

In this way, the position of each grinding surface of the grinding wheel is memorized based on the amount of movement of the contact from the movement start point. First, for each grinding surface of the grinding wheel on which truing has been completed, the contactor is moved as described above until contact is detected, the amount of movement is detected, and the position of each grinding surface after truing is determined. remember.

Next, when a workpiece is processed using the grinding wheel, each grinding surface of the grinding wheel is displaced because the grinding wheel undergoes thermal expansion in the radial and axial directions. Further, the ground surface is worn down by a certain thickness due to wear compared to the ground surface after the previous truing was completed.

Therefore, in this state, we measured the amount of movement of the contact by moving the contact again until it came into contact with each grinding surface in the same way as before, and the position of each grinding surface immediately before truing was determined by moving the contact. The value is stored in the storage unit 14 as a quantity.

The displacement detection unit 16 determines, for each grinding surface, the ground surface immediately after the previous truing of each ground surface as a reference based on the amount of movement of the contactor measured immediately after the previous truing and the amount of movement of the contactor immediately before the current truing. Find the displacement. The truing control unit 18 corrects the influence of the displacement of the grinding surface in the normal direction caused by the axial displacement of the grinding wheel from the displacement of each grinding surface, and calculates the true grinding surface in the normal direction. Find the displacement of
It has a function to determine the trajectory of the truing tool so as to uniformly grind a certain thickness from each grinding surface immediately before truing, and to operate the truing tool according to the trajectory.

The present invention consists of the above configuration.

〔Example〕

The present invention will be described below based on specific examples.

FIG. 2 is a partial configuration diagram of the present truing device showing the relationship among the truing control section, the truing tool drive device, and the grinding wheel of the present truing device. FIG. 3 is a partial configuration diagram of the present apparatus showing the relationship among the truing tool drive device, the contact, the contact drive device, and the grinding wheel. Moreover, FIG. 4 is a partial configuration diagram of the present device showing the relationship between the contactor, the contactor drive device, and the grinding wheel.

A fluid bearing metal 207 that rotatably supports a grindstone shaft 201, which is a rotating shaft of the grindstone wheel 20, is disposed on the grindstone head 210. A pulley 202 for transmitting rotational force is provided at the other end of the grinding wheel shaft 201, and the grinding wheel 20 is rotated by power being transmitted by a drive motor (not shown).

On the other hand, a flange 206 provided at the center of the grindstone shaft 201 engages with a movable block 205, and a fluid thrust bearing is formed between the movable block 205 and the flange 206. The movable block 205 is threadedly engaged with the feed screw 204, and the feed screw 20
4 is directly connected to a rotating shaft of a servo motor 203 for moving the grindstone shaft 201 in the axial direction. Therefore, when the servo motor 203 is rotated, the feed screw 204 rotates, and the movable block 205 that is threaded therewith moves in the axial direction of the feed screw 204.
Therefore, the grinding wheel shaft 201 can receive the moving force from the movable block 205, move in the axial direction, and move the grinding wheel in the same direction.

Further, a truing tool drive device is provided above the grindstone head 210. A support stand 405 is fixed on the whetstone head 210, and a guide stand 410 is provided on the support stand 405 to enable movement of the traverse stand 409 in the direction of the whetstone axis. The traverse table 409 can be moved in the direction of the grindstone axis by a traverse cylinder 407'. The traverse table 409 is provided with a reciprocating table 407 that is arranged to move the truing tool 2 in the normal direction of the grinding wheel 20 . A cutting ram 403 is provided in the inner center hole of the advancing/retracting table 407, and the cutting ram 403 is threadedly engaged with a feed screw directly connected to the central axis of a servo motor 402 that controls the amount of cutting. Servo motor 40
The support head 401, which supports the truing tool 2 by rotation of the grinding wheel 2, is movable in the radial direction of the grinding wheel relative to the reciprocating table 407. Further, a pilot pen 408 is provided at one end of the advancing/retracting table 407, and the pilot pen 408 is engaged with a template 406 fixed to the support table 405. Further, a piston is provided on the flange portion of the advancing/retracting table 404, and this piston interacts with a cylinder 416 to transmit a force for pressing the pilot pen 408 to the tracing surface of the template 406. Activate the traverse cylinder 407,
When the traverse table 409 is actuated, the truing tool 2 moves in the direction of the grinding wheel axis, and also moves in the radial direction of the grinding wheel in the shape of the template due to the action of the template 406. Therefore, the shape of the template 406 is
By creating the same shape as the grinding surface of the grinding wheel, it is possible to true the same shape along the grinding surface of the grinding wheel.

Next, the contactor and the contactor drive device will be explained. FIG. 4 is a diagram showing its configuration. A support stand 801 for fixing the whetstone head 210 is provided above the whetstone head 210. A guide member 811 extending in the axial direction of the grinding wheel shaft is provided on the support stand 801.
1 is engaged with a sliding base 812. Sliding table 81
A guide cylinder 813 that accommodates the reciprocating ram 802 is disposed above the reciprocating ram 802 . The advancing/retracting ram 802 is housed inside the guide cylinder 813.
The advancing/retracting ram 802 is engaged with a feed screw 803 . The feed screw 803 is a servo motor 804 for advancing and retreating.
When the servo motor 804 rotates, the advancing/retracting ram 802 moves forward and backward in the normal direction of the grinding wheel. Also, the shift cylinder 81
0, the piston disposed inside the slide table 8
12 and slide the slide table 812 along the guide member 811. Therefore, the shift cylinder 81
By operating the servo motor 804, the contactor can be moved in the axial direction of the grinding wheel, and by operating the servo motor 804, it can be moved in the normal direction. Advance/retreat ram 80
A contactor 6 having a first contact portion 6a and a second contact portion 6b shaped as shown in the figure is disposed at the tip of the vibration sensor 1.
0 is joined.

FIG. 5 is a configuration diagram showing the configuration of the electrical system of this device. Control of this control device is performed by an electronic computer. An electronic computer has a CPU 30 and an interface 3 interposed between it and input/output devices.
3, 34 and a memory 35. Also CPU3
2 is connected to a data input device 31 and a detection circuit 32 that receives signals from a vibration sensor and detects contact between the contact and the grinding surface. Drive units 36, 37, 38 for driving each servo motor 203, 402, 804 and a hydraulic control circuit 39 for driving each hydraulic cylinder are connected to the CPU.

FIG. 6 is a flowchart showing the flow of the processing method performed by this computer. Also, Figures 7 and 8
The figure is a principle explanatory diagram illustrating the principle for detecting displacement of the grinding surface of a grinding wheel using this contactor.
Steps 100 to 116 are steps for detecting the position of each grinding surface 20a and 20b of the grinding wheel with respect to the origin of the contact, and correspond to a contact movement amount detection section. In the arrangement shown in FIG. 7a, when the contactor 6 is oriented in the U-axis direction indicating the direction toward the center in the normal direction of the grinding wheel, the first contact portion 6a
is moved until it comes into contact with the grinding surface 20a and is detected by the vibration sensor. When contact occurs, the contact drive device is stopped and the feed amount is stepped.
At 104, it is stored as MR. That is, this
The value of MR represents the position of the ground surface 20a with respect to the origin of the contact. After returning the contact to the origin in step 106, in order to measure the position of the grinding surface 20b, the shift cylinder 810 is actuated to move the contact 6 to the K position, as shown in FIG. 7b.
to the left in the drawing, and the second contactor 6b is shifted to a predetermined position in the X direction, that is, in the grindstone axis direction. Then, in step 110, as above,
After feeding the contact until it makes contact, the feeding amount is stored as NR. That is, the value of NR indicates the position of the ground surface 20b with respect to the origin of the contact. Thereafter, in step 116, the contactor 6 is returned to its original position. In this way, the position of the grinding surface immediately before truing is detected as the amount of movement of the contact. Next, in step 118, the displacement of the feed amount of the contact is determined. That is, as will be described later, in MO and NO, each movement amount of the contactor measured immediately after truing the grinding surface of the grinding wheel in the previous truing process is stored. Therefore, the difference between the positions of the respective grinding surfaces is calculated and the values are stored as A and B. Step 118 corresponds to the displacement detection section described above. 7th
In FIG. c, dash-dotted lines 21a and 21b indicate the position of the grinding surface of the grinding wheel immediately after the previous truing, as seen from the coordinate system fixed to the grinding wheel head. Therefore, the values of A and B calculated in step 118, respectively, are calculated for each grinding surface 20 as shown.
It represents the displacement of a and 20b in the U-axis (normal line) direction, respectively. Regarding the intersection lines 21c and 20c of the respective grinding surfaces of the grinding wheel, as shown in the figure, the grinding wheel is shifted in the axial direction, that is, the X-axis direction due to thermal expansion, etc., so the intersection line 20c is It can be seen that it is shifted by Δx in the axial direction. Moreover, as shown in FIG. 8, the U direction component ΔY and the X direction component ΔX of the displacement of the intersection line 20c of the ground surface with respect to the intersection line 21c of the ground surface immediately after the previous truing are expressed as the angle formed by the ground surface. It can be expressed by the following equation, where θ.

ΔX=(AB) sin θ·cos θ ΔY=Bcos ² θ+Asin ² θ Here, in this embodiment, θ is set to 30 degrees.
Therefore, ΔX=√3/4・(A−B) ΔY=1/4・(A+3B) Next, during this truing, the grinding wheel
Since the displacement is Δx in the axial direction, step 122
In this step, the servo motor 203 is driven to move the grinding wheel by -ΔX, and in the X-axis direction, the intersection line 20c is made to coincide with the intersection line of the grinding surface immediately after the previous truing. Next, in step 124, the servo motor 402 is driven to move the truing tool forward by ΔY+C in the normal direction (Y-axis direction). That is, ΔY is the correct displacement of the grinding surface in the normal direction after correction, and C represents the thickness of the grinding wheel. By correcting the position of the truing tool with respect to the position during the previous truing in this way, the grinding wheel can uniformly grind the grinding surface by the thickness C just before the truing. Next, in step 126, the traverse cylinder 40
7 is driven, the truing tool 2 is operated in a predetermined trajectory while tracing the template 406, and the grinding wheel is ground. After grinding, the traverse cylinder 407 is operated in the opposite direction to move the truing tool 2 in the positive direction of the X-axis to the origin position, thereby completing the truing. After that, in step 130, the grinding wheel head is moved in the normal direction by ΔY+C.
only move forward. That is, when such a grindstone head is moved, the relative distance of the grinding surface to the workpiece becomes the same as that immediately after the previous truing. The next steps 132 to 144 are a process in which the contact is moved in the normal direction to the ground surface immediately after truing, and the position of the ground surface is measured and memorized with respect to the origin of the contact. That is, for each truing, the contacts are aligned and the measurement system is calibrated. Steps 132 and 134 are similar to steps 100 and 102 described above. Also, in step 136, the detected movement amount is used in step 118 of the next truing process.
It is stored in the MO as the position of the ground surface immediately after the previous truing used in . step
After returning the contact to the origin at step 138, the contact is shifted by K in the -X direction, and at step 140, the feed amount is measured in the same manner for the other grinding surface 20b. That value is stored in step 142 as NO. Next, in step 144, the contactor is returned to its origin, and the process ends. Through the above-described processing, the grinding wheel can correct errors caused by displacement in the axial direction and accurately true the grinding surface.

By using the template used in the above example, instead of determining the truing trajectory, the NC
Trueing may be performed in a predetermined shape through control. That is, as shown in FIG. 9, the truing locus may be generated by a mechanism of feed screws 903, 904 and servo motors 901, 902 that can move the truing tool 2 in the X direction and the U direction, respectively. In this case, instead of shifting the grinding wheel by Δx in the X-axis direction as in this embodiment, the truing start point P0 is shifted relative to the previous truing start point P1 as shown in FIG. Only ΔX and ΔY may be corrected.

Further, instead of sliding the traverse table along the template, the template may be slid.

〔Effect of the invention〕

In summary, the present invention is designed to adjust the displacement of the grinding surface of the grinding wheel to the previous truing so that even if the grinding wheel is displaced in the axial direction, the truing of both grinding surfaces of the grinding wheel can be performed uniformly with a constant thickness. The position of the grinding surface immediately after being ground is determined as a reference, and the truing trajectory is corrected based on this displacement. Therefore, according to this device, the angular type grinding wheel is displaced in the radial and axial directions. Accurate truing with uniform thickness is possible. Therefore, the service life of the grinding wheel can be extended, and the workpiece can be processed with high precision.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the concept of the present invention. FIG. 2, FIG. 3, and FIG. 4 are configuration diagrams of a mechanical part of a truing device according to an embodiment of the present invention. Of these, Fig. 2 is a mechanical diagram showing the relationship between the grinding wheel and the truing tool drive device, Fig. 3 is a mechanical diagram showing the relationship between the contactor, the truing tool drive device, and the grinding wheel, and Fig. 4 is a mechanical diagram showing the relationship between the contactor, the truing tool drive device, and the grinding wheel. FIG. 2 is a mechanical diagram showing the configuration of a contact and a contact drive device. FIG. 5 is a configuration diagram showing the configuration of the electrical system of the device of this embodiment. FIG. 6 is a flowchart showing the processing of the computer used in the same example. 7th
Figure 8 is an explanatory diagram explaining the principle of the process for determining the displacement of the grinding surface, and Figure 9 is
FIG. 10 is a configuration diagram of a truing tool drive device showing a modification of the same embodiment, and FIG. 10 is an explanatory diagram of its operation. 2... Truing tool, 4... Truing tool drive device, 6... Contact, 8... Contact drive device, 9... Vibration sensor, 12... Contact movement amount detection section, 14... Storage section, 16...displacement detection section,
18... Truing control section.

Claims (1)

[Scope of Claims] 1. A truing tool that performs truing by grinding the grinding surface of a grinding wheel; a truing tool drive device capable of moving the truing tool in the normal direction and axial direction of the grinding wheel; and the grinding wheel. a contactor capable of contacting each grinding surface of the grinding wheel; a contactor driving device capable of moving the contactor in at least the normal direction of the grinding wheel; and detecting that the contactor contacts the grinding surface of the grinding wheel. a contact detection sensor; and inputting a signal from the contact detection sensor to operate the contact drive device from its movement starting point until it is detected that the contact has contacted each grinding surface of the grinding wheel. , a contactor movement amount detection unit that detects the movement amount of the contactor; a storage unit that operates the contactor movement amount detection unit immediately before and after truing and stores each detected movement amount; and in the storage unit. The displacement of each grinding surface of the grinding wheel immediately before truing with respect to each grinding surface of the grinding wheel immediately after the previous truing is calculated from the amount of movement stored and detected immediately before truing and the amount of movement detected immediately after the previous truing. A displacement detection unit detects, and a displacement of the grinding surface of the grinding wheel detected by the displacement detection unit determines the operation of the truing tool during the previous truing, relative to the grinding surface of the grinding wheel immediately before truing. A truing device for an angular type grinding wheel, comprising: a truing control section that controls the truing tool drive device so that each grinding surface of the grinding wheel immediately before truing is trued to the same thickness by correcting the trajectory; 2. The contact has first and second contact tips that can each contact one of the two grinding surfaces of the grinding wheel, and these are integrally formed, and the contact drive device includes: The truing device for an angular type grinding wheel according to claim 1, further comprising a mechanism capable of moving in the axial direction of the grinding wheel. 3. The angular type according to claim 1, wherein the relative trajectory of the truing is generated by tracing a template having the same shape as the shape of the grinding surface of the grinding wheel. Grinding wheel truing device. 4 Correction of the relative trajectory of the truing is as follows:
With respect to the axial direction of the grinding wheel, the grinding wheel is moved in the axial direction, and with respect to the normal direction of the grinding wheel, the position of the truing tool with respect to the template is moved in the normal direction. A truing device for an angular type grinding wheel according to claim 3.