JPH0457465B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a cylindrical grinder for cylindrical grinding of magnetic heads and the like.

<Prior art> Generally, in the manufacturing process of magnetic heads, machining for forming curved surfaces of the media sliding surfaces of magnetic heads that come into contact with magnetic recording media such as magnetic tapes is performed by grinding using a cylindrical grinder and wrapping using wrapping tape. Are known. Among these processing methods, the former method of grinding using a cylindrical grinder is more likely than the latter method of wrapping using a wrapping tape to (1) require a larger absolute amount of processing (2) chipping, cracking, or (3) There are characteristics such as the tendency to generate heat due to grinding on the machined surface, so the grinding conditions of the workpiece (magnetic head) must be strictly controlled. Above all, the amount of grinding needs to be controlled with high precision because it is necessary to grind the gap depth of the magnetic head to a predetermined dimension. In addition, multi-track magnetic heads used in digital magnetic recording and reproducing devices, which have undergone remarkable technological development in recent years, have a larger number of tracks than magnetic heads normally used in analog magnetic recording and reproducing devices, and are capable of high-density recording. Since regeneration is required, the gap depth of each track must be formed with high precision and uniformly.
By the way, the amount of grinding on a cylindrical grinder is controlled by
In order to eliminate unstable factors such as dimensional changes due to wear of the grinding wheel and thermal expansion of the workpiece due to heat generated during grinding, some machines are equipped with an automatic sizing device and are CNC (computer numerically controlled). In addition, as a dimensional control method for grinding or wrapping the gap depth of the magnetic head to a predetermined dimension, there is a visual recognition method using an optical microscope and a change in the resistance value of a resistor formed in the gap part of the magnetic head. There are known methods for detecting.

<Problems to be Solved by the Invention> However, in order to improve the surface roughness of the ground surface of the workpiece, when an elastic grinding wheel using a resinoid binder is used as a grinding wheel, due to the characteristics of the grinding wheel, The depth of cut of the grindstone and the amount of grinding of the workpiece are not necessarily the same.
Even with the addition of a CNC device, it was difficult to control the amount of grinding with high precision using such devices that did not have a feedback control system. Furthermore, if the visual recognition method using an optical microscope or the resistance value detection method of a resistor is used, compared to the automatic sizing device or CNC device described above,
The amount of grinding can be controlled with high precision, but unless there is a control system that constantly measures the resistance value of the resistor during grinding and corrects the angle of the surface to be ground, the gap depth for each track can be controlled with high precision. It was difficult to grind and form uniformly. In addition, when using the resistance value detection method of the resistor, due to non-uniformity in the resistance value of the resistor for each lot of the resistor head board and fluctuations in the resistance value of the resistor due to heat generation on the machined surface during grinding, It has been difficult to uniformly grind the gap depth for each track with high precision.

The present invention has been made in view of the above-mentioned problems, and it is possible to control with high precision the amount of grinding during cylindrical grinding that forms the gap depth of the magnetic head, and also to control the gap depth of each track of the magnetic head with high precision. To provide a cylindrical grinder capable of uniformly grinding grains with high precision.

<Means for Solving the Problems> In order to achieve the above object, the cylindrical grinding machine according to the present invention provides a cylindrical grinder that has a grinding surface in a direction perpendicular to the traverse axis at both ends of the surface to be ground of the magnetic head in the traverse axis direction. A measuring means for measuring the amount of displacement, a resistor having a predetermined resistance value and provided in advance on the magnetic head for measuring the amount of grinding of the ground surface of the magnetic head, and a resistor perpendicular to the traverse axis. a Y-axis moving table that can be moved in parallel in the direction;
A rotary table that is rotatable in the same plane as the Y-axis moving table, and the parallelism of the surface to be ground of the magnetic head with the traverse axis based on the amount of displacement determined by the measuring means before cylindrical grinding. parallelism detection means for determining the parallelism; and for making the ground surface of the magnetic head parallel to the traverse axis by rotating the rotary table based on the parallelism before cylindrical grinding. a grinding surface setting means, a resistance value measuring means for constantly measuring the resistance value of the resistor during cylindrical grinding, and a grinding amount determined from the resistance value determined by the resistance value measuring means during cylindrical grinding. a tilt angle detecting means for determining the tilt angle of the surface to be ground of the magnetic head from the grinding amount; and a tilt angle detecting means for determining the tilt angle of the ground surface of the magnetic head from the grinding amount; a position correction means for correcting the absolute position of the magnetic head by rotating to cancel the tilt angle and simultaneously moving the Y-axis moving table; and the resistance value detection means. The present invention is characterized by comprising a grinding end means for ending cylindrical grinding when the determined resistance value reaches a predetermined value.

<Operation> Before cylindrical grinding, the amount of displacement at both ends of the surface to be ground of the magnetic head is measured by the measuring means, the parallelism is determined by the parallelism detecting means, and the rotary table is driven according to the measured value. After the surface to be ground is made parallel to the traverse axis by the surface to be ground setting means, cylindrical grinding is started.

During cylindrical grinding, the resistance value of the resistor elements provided at both ends of the surface to be ground is measured by a resistance value measuring means, the amount of grinding is determined from this resistance value, and the amount of grinding is used to detect the inclination angle. The angle of inclination of the surface to be ground is determined by means. The rotary table is rotated by the position correction means according to the tilt angle thus obtained, and the Y
The absolute position of the upper magnetic head is corrected by moving the axis movement table to offset the tilt angle.

The grinding end means detects that the resistance value detected by the resistance value detection means has reached a predetermined value, and ends the cylindrical grinding.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of the main body of the machine.

23 is a bed of the main body of the machine, and a grindstone head 21 is provided on the top of the bed. A static pressure air bearing 17 that pivotally supports the grinding wheel 18 is provided on the grindstone head 21, and the static pressure air bearing 17 is connected to a bearing drive motor 19 via a bearing drive belt 22.

The grinding wheel 18 is connected to the shaft constant drive motor 1.
By driving 9, it is rotated at a constant rotation speed in the same direction as the rotation direction of the motor. Further, the other end 21a of the grindstone head 21 is provided with a surface 14a to be ground of the magnetic head 14 (hereinafter simply referred to as the magnetic head) which is the object to be ground, and a traverse axis (hereinafter referred to as the X axis) during grinding of the magnetic head 14. An electric micrometer prong 15 and a stylus 16 at the tip of the prong are provided for measuring parallelism. The probe tip stylus 16 is configured to be displaced within a measurable range in the direction of the arrow in FIG. 1A to measure the parallelism.

On the other hand, in addition to the grindstone head 21, an X-axis moving table 1 for traverse feeding is mounted on the bed 23. The X-axis moving table 1 is supported and guided by a cross roller guide 25, and is freely moved within a predetermined movement range in the X-axis direction by a ball screw (not shown) and a DC servo motor 2. Further, on the X-axis moving table 1, a cross roller guide (not shown) guides and supports the table, and a ball screw (not shown) and a pulse motor 4 cause a predetermined movement in the cutting direction of the workpiece (hereinafter referred to as the Y-axis). A Y-axis moving table 3 is mounted that can freely move within a range. A sliding plate 24 is fixed on the Y-axis moving table 3, and the upper surface of the sliding plate 24 is coated with a resin film.

A rotary table 5 is mounted on the sliding plate 24 so as to be rotatable within the X-Y plane about a pivot shaft 9.

The lower surface of the rotary table 5 is in contact with the upper surface of the sliding plate 24, so that it can rotate freely without any lubrication oil. A worm wheel 8 is fixed to the top surface of the sliding plate 24, and a worm wheel 8 is fixed to the top surface of one rotary table 5.
A worm shaft 7 is supported on the shaft so as to mesh with the worm shaft 7.

The worm shaft 7 is rotationally driven by a motor 6 fixed on the rotary table 5, and the rotary table 5 rotates about a pivot shaft 9 supported on the sliding plate 24 with respect to the sliding plate 24. ,
It can be rotated freely within the range where the worm wheel 8 and the worm shaft 7 engage.

On the rotary table 5, a swing bearing stand 10 is placed so that the work holder 12 to which the magnetic head 14 is attached can swing around the swing plate 12a.
11. A swing shaft drive motor 13 for swinging the work holder 12 is disposed at one end of the swing plate 12a, and a magnetic head 14 attached to the work holder 12 drives the swing shaft drive motor 13. It can be oscillated by continuous reversal driving.

Therefore, the magnetic head 14 mounted on the work holder 12 is moved along the X axis with respect to the grinding wheel 18 which is rotationally driven by the bearing driving motor 19 via the bearing driving belt 22 and the static air bearing 17. A table 1 provides traverse drive, a Y-axis moving table 3 provides a cut for each traverse, and a swing shaft drive motor 1
3, the cylindrical grinding process is performed while being given an oscillating motion about the oscillating shaft 12a.

In addition, the surface 14a to be ground of the magnetic head 14 is rotated by the motor with respect to the worm wheel 8 fixed to the upper surface of the sliding plate 24, with the pivot axis 9 as the center, regardless of whether it is being ground or not. The angle with respect to the X-axis can be constantly adjusted by rotating the rotary table 5, which is rotated by rotating the worm shaft 7 using the rotary table 6. A diamond dresser 20 is fixed to the grinding wheel facing surface 10a of the swing bearing stand 10, and the grinding wheel is driven by the X-axis drive table 1 for traverse drive and the Y-axis drive table 3 for cutting. 18 truings and dressings can be performed.

FIG. 2 is a block diagram of the entire system.

In the figure, 26 is the aforementioned machine body, 27 is the bearing drive motor 19 mounted on the machine body 26,
The DC servo motor 2, the pulse motor 4, the motor 6, the swing shaft drive motor 1
Control box 27 shows a control box in which each controller, driver, and power source of 3 are housed.
An external keyboard 28 is connected to which the machine body 1 can be remotely controlled from the outside. Next, the control box 27 is connected to the CPU 2 for controlling this system via the I/O unit 30.
9 is connected, and the I/O unit 30 drives a floppy disk that stores various programs for operating this system or a floppy disk for recording and storing various data during grinding. A floppy disk drive 31 is connected. As described above, this system is composed of six elements: the machine body 26, the control box 27, the external keyboard 28, the CPU 29, the I/O unit 30, and the floppy disk drive 31.
7. The three elements of the external keyboard 28 can be called the operating system of this system, and the CPU 29, I/O unit 30, and floppy disk drive 31 can be called the processing system of this system. Therefore, all operational controls of this system are controlled by the system drive program inputted from the floppy disk drive 31 via the I/O unit 30 and by the thin film disposed on the magnetic head 14 attached to the machine body 26. The resistance value of the resistor and the measurement data measured by the electric micrometer probe 15 are sent to the I/O unit 30.
The measurement and calculation data associated with these measurements and grinding processes are input to the CPU 29 via the I/O unit 30 and processed.
The data can be recorded on a floppy disk by the floppy disk drive 31 via the floppy disk drive 31.

In this system, once the magnetic head 14, which is the workpiece, is attached to the work holder 12 and the entire system is started, the subsequent measurement and grinding processes can be operated fully automatically. One of its features is that it is possible to monitor the measurement and grinding process status on the screen at any time and simultaneously with the progress of the process. By recording the data on the machine, it is also possible to output measurement and grinding data at any time even after all processes have been completed.

In the cylindrical grinding machine system configured in this manner, first, an outline of the operating sequence of the system will be explained.

FIG. 3 shows an overview flowchart of the operating sequence of this system. First, as shown in operation 1, after the system is powered on, the X-axis drive table 1 and Y-axis drive table 3 of the machine body are returned to the measurement and machining radius points in order to perform measurement and grinding of the magnetic head 14. Next, truing and dressing of the grinding wheel 18 shown in operation 2 is performed, and the process moves to operation 3. In operation 3, after setting the magnetic head 14 on the work holder 12, the X of the grinding surface 14a of the magnetic head 14 is
The parallelism with respect to the axis is measured, and if the measured value does not satisfy a predetermined tolerance, the parallelism is corrected until the tolerance is satisfied.

Next, as shown in operation 4, the magnetic head 14 is ground. At this time, simultaneously with the grinding process, the gap depth of the magnetic head 14 is detected and calculated, and the parallelism is corrected so that the gap depth on each track becomes uniform for each traverse. When the amount of grinding set at the time of system startup is reached, the grinding cycle is ended and the grinding process of the next magnetic head is started.

As mentioned above, the operation of this system is as shown in Figure 3.
It can be broadly classified into actions. Next, these four operations will be explained in more detail.

Γ Operation 1 First, after turning on all the power to the processing system and operation system of this system, in order to fully automatically control the measurement and grinding of the magnetic head 14 by the CPU 29 of the processing system, By driving the axis moving table 1 and the Y-axis moving table 3 in predetermined directions, and activating a limit switch (not shown) disposed at the stroke end of each of the moving tables, The position is set as the measurement/processing origin of the magnetic head 14 and is recorded in the CPU 29 of the processing system. This operation enables the CPU 29 to control the drive of the machine body 26 of the operating system based on the measurement/processing origin until a series of grinding processes in this system are completed.

This operation, that is, the initialization of the system, is performed by loading a measurement/processing program prepared in advance by the floppy disk drive 31 of the processing system into the CPU 29 after the system is powered on.

Next, the process moves to truing and dressing of the grinding wheel shown in operation 2.

Γ Operation 2 In operation 2, the X-axis drive table 1 and Y-axis drive table 3 are driven from the measurement/processing origin shown in operation 1, and the diamond plate fixed to the grinding wheel facing surface 10a of the rocking bearing stand 10 is driven. The dresser 20 is moved to a position at a constant interval from the outermost periphery of the grinding wheel 18 (workpiece grinding surface). Here, the above-mentioned fixed interval means that when grinding is performed using the same grinding wheel as when finishing the last grinding,
Processing system CPU based on the grinding data at the end of the previous grinding
29 indicates the interval at a position several hundred μm away from the outer circumference diameter of the grinding wheel at the end of the previous grinding process, and when using a different grinding wheel from the one used at the end of the previous grinding process, the corresponding grinding wheel is connected to a hydrostatic air bearing. 1
7, the outer circumferential diameter of the grinding wheel is measured in advance, and the measurement data is input into the processing system CPU 29 to determine the grinding wheel.

As shown above, insert the diamond to the specified position.
After moving the dresser 20, an instruction (input) to start the truing and dressing cycle of the grinding wheel 18 is given using the external keyboard 28 of the operation system.

A signal inputted from the external keyboard 28 is once transferred to the processing system CPU 29, starts a program for truing and dressing, and starts a truing and dressing cycle. The reason for instructing the start of the cycle from the external keyboard 28 of the operating system is to prevent malfunction of the cycle due to a measurement error in the outer diameter of the grinding wheel in the operating system machine body 1, such as when the grinding wheel is changed. If safety is sufficiently confirmed, the CPU 29 can directly instruct the start of the cycle.

In the truing and dressing cycle, the diamond dresser 20 is moved by a predetermined depth of cut from a position 1/2 the thickness of the grinding wheel 18 using the Y-axis drive table 3, and when the movement is completed, the A reciprocating traverse is made by the shaft-driven table 1. Truing and dressing are performed by repeating this cycle.

When the truing and dressing are completed, the machine moves to the measurement processing origin again and starts the next operation 3.

Γ Operation 3 In operation 3, the parallelism of the ground surface 14a of the magnetic head 14 to the traverse axis, that is, the X axis, is measured using the electric micrometer probe 15 and the same stylus 16, and the measured value satisfies a predetermined tolerance. If not, the parallelism is corrected and remeasured so that the parallelism falls within the allowable value, and the parallelism of the surface 14a to be ground by the magnetic head is determined.

First, at the end stage of operation 2, since the magnetic head 14 is located at the measurement processing origin, by driving the X-axis drive table 1 and the Y-axis drive table 3, the ground surface 14a of the magnetic head 14 is
Then, the magnetic head 14 is moved to a position where it comes into contact with the tip stylus 16 of the electric micrometer probe 15 disposed on the other end 21a of the grindstone head 21. (Position C in FIG. 1) Here, the stylus 16 is adjusted and supported vertically below, as shown in FIGS. 1 and 4B, and the magnetic head is attached to the ground surface 14a
Gap portion 1 of the magnetic head 14 located in the center of
The stylus tip 16a is in contact with the periphery of the stylus 4b.

Further, at this time, the work holder 12 is positioned by the swing shaft drive motor 13 so that the surface 14a to be ground by the magnetic head becomes a vertical plane. From this state, by driving the X-axis drive table 1, the magnetic head grinds the ground surface 14 as shown in FIG. 4A.
The stylus 16 is caused to traverse back and forth within the full width in the longitudinal direction of a. The stylus 16 is displaced only in the direction perpendicular to the traverse direction (in the direction of the arrow B in FIG. 4), and this direction is taken as the measurement direction. However, if the magnetic head ground surface 14a is not parallel to the traverse axis, the stylus 16 moves in the measurement traverse direction. The absolute amount of displacement at both ends of the traverse and the distance traveled by the traverse are input to the processing system CPU 29, and through calculation processing, the degree of parallelism with the traverse axis is displayed as an angle, and the calculated angle and predetermined tolerance value are displayed. Compare with (angle). Here, when the calculated angle is within the allowable value (that is, when the calculated angle is smaller than the allowable value), at that stage, the parallelism of the magnetic head to be ground surface 14a with respect to the traverse axis is measured and parallelism is measured. After completing the degree correction, proceed to the next operation 4. When the calculated angle is outside the allowable value, that is, when the calculated angle is larger than the allowable value, the motor 6 rotates the rotary table 5 in the direction of decreasing parallelism. 4. As shown in Fig. 4A, rotate the magnetic head 14 in the relevant direction about the pivot rotation axis 9 by an angle such that the parallelism with the traverse axis is 0, and the magnetic head grinding surface 14a and the traverse axis are rotated. Correct the parallelism and measure the parallelism again in the same manner as described above.

In this manner, the violence degree measurement and parallelism correction are repeated until the calculated angle falls within the allowable value, and when this condition is satisfied, the process moves to the next operation 4.

Here, the area around the magnetic head gap part 14b, which the stylus tip 16a contacts, of the magnetic head ground surface 14a is diced with high precision.
When measuring the parallelism mentioned above, the stylus tip 1
Since the straightness of the surface traced by 6a is finished to such an extent that it can be ignored with respect to the parallelism tolerance, it is assumed that the influence of the straightness on the parallelism measurement is not considered.

Further, FIG. 5 shows a flowchart of operation 3, in which the movement to the angle correction position in flow 3 means that the parallelism of the magnetic head to be ground surface 14a is measured and the parallelism correction is performed. In this case, if parallelism correction is performed at the position of the magnetic head 14 after parallelism measurement, the magnetic head ground surface 14a and the stylus tip 16a will interfere, and when parallelism is measured again, the measurement range of the electric micrometer will be exceeded. When performing parallelism correction, the magnetic head 14 is moved using the Y-axis moving table to a position where the ground surface 14a of the magnetic head does not come into contact with the stylus tip 16a. The movement is called movement to the angle correction position.

Γ Operation 4 The operations 1 to 3 described above are pre-processes before starting the grinding process, and in operation 4, the magnetic head 14 is cylindrical grinded. Here, the configuration of the gap portion 14b of the surface to be ground 14a of the magnetic head 14 will be briefly described.

The gap portion of the magnetic head 14, which is the workpiece used in this embodiment, has a structure as shown in FIG. In FIG. 6, reference numeral 33 denotes tracks formed of a thin film, and resistors 32, also formed of a thin film, are arranged at both ends of the tracks arranged at equal intervals of about ten tracks. This resistor 32 has a predetermined specific resistance value R before the grinding process,
The resistance of the resistor 32 when the gap portion 14b is ground in the direction of the arrow in FIG. 6, and the total length of the resistor in the direction of the arrow is reduced from the total length l before the grinding to l' during the grinding process. When the value is R′, the relational expression shown below holds between these.

R×l×R'×l'... Therefore, the resistance value R' of the resistor 32 is constantly measured during grinding, and the measured data is sent to the processing system CPU 29.
The initial (inherent) resistance value R of the resistor, which was also input to the CPU 29 after system startup, and the total length l of the resistor before grinding are calculated using the above formula to calculate the resistance during grinding at any time. The total length l' of the body 32 can be found. Here, the resistor 32
The resistance value R' is constantly measured by a resistance value measuring circuit (not shown) built into the operation system control box 27 shown in FIG. 2, and the measured value is sent to the processing system CPU 29. It is configured to be input.

The magnetic head 14 having the gap portion configured as described above is in a position where the surface to be ground 14a is in contact with the stylus 16 of the electric micrometer shown in FIG. 1 at the stage when operation 3 is completed. From this position, the Y-axis drive table 3 and the X-axis drive table 1 move a predetermined distance away from the grinding surface 18a of the grinding wheel 18 (see FIG.
(the position shown in ).

Here, the position a predetermined distance away from the grinding surface 18a of the grinding wheel 18 means the distance from the position of the magnetic head 14 at the end of the previous grinding process. The position (in other words, the outer diameter of the grinding wheel 18) is the processing system.
The data is processed by the CPU 29 and recorded on a floppy disk stored in the processing system floppy disk drive 31, and is determined based on the previous data.

However, if the grinding wheel to be used is different from the previous one, it is necessary to input the outer diameter of the grinding wheel to be used this time into the processing system CPU 29 after the system is started.

As shown above, move the magnetic head 14 to the predetermined position.
After moving the magnetic head 14, the operator instructs (inputs) to start the grinding cycle of the magnetic head 14 using the external keyboard 28 of the operation system. The signal input from the external keyboard 28 is once transferred to the processing system CPU 29,
Start the program for grinding and start the grinding cycle.

The reason why the external keyboard 28 of the operation system is used to instruct the start of the cycle is to prevent malfunction of the cycle due to a measurement error in the outer diameter of the grinding wheel in the machine body 1 of the operation system, such as when the grinding wheel is changed. If safety is sufficiently confirmed, the CPU 29 can directly instruct the start of the cycle. In the grinding cycle, when the start of the cycle is instructed from the external keyboard 28, the grinding wheel 18 is first rotated at a constant speed by the bearing drive motor 19, and then the work holder 12 is rotated by the swing shaft drive motor 13. The oscillations are interlocked while maintaining a 90° oscillation angle.

Then, the magnetic head 14 is moved by the X-axis drive table 1 to the grinding start and end positions shown in FIG. 1D. In this state, first, the Y-axis moving table 3 applies a predetermined depth of cut to the rotating grinding wheel 18 in the direction in which the magnetic head 14 approaches the grinding wheel 18 (Y-axis + direction). When the operation is completed, the X-axis drive table 1 causes the X-axis drive table 1 to perform a reciprocating traverse drive in the X-axis (traverse axis) direction. Here, the stroke of the reciprocating traverse of the magnetic head 14 is within a range in which the grinding wheel 18 does not come into contact with the swing bearing stands 10, 11 and the diamond dresser 20 fixed to the grinding wheel facing surface 10a of the swing bearing stand 10. Both the grinding start and end positions can be set to any stroke amount or position within the range from the system keyboard of the processing system CPU 29 before the start of the grinding cycle.

The magnetic head 14 rotates the rotating grinding wheel 18 by a swing shaft drive motor 13 and a Y-axis drive table 3 to make a cut.
Traverse drive is provided by the X-axis drive table 1, and cylindrical grinding is performed.

Next, as described above, as the Y-axis drive table 3 applies a predetermined depth of cut for each reciprocating traverse, the magnetic head 14 approaches and then contacts the grinding wheel 18 to perform the grinding process. However, when the grinding of the 14 gap portions 14b shown in FIG. 6 begins, the resistors 32 arranged at both ends of the track 33 are removed by grinding, and the control box 27 of the operating system shown in FIG. The resistance value R' of the resistor 32, which is constantly measured by the built-in resistance value measuring circuit, fluctuates. This makes it possible to know the total length l' of the resistor 32 during grinding, and as shown in FIG. l _L , and the resistors arranged on the right side are 3
2R, and if the total length during grinding is l _R , the total lengths of the resistor during grinding, l _L and l _R , are reduced by grinding at each traverse, and the value is changed by the processing system CPU 29 every time the total length changes. Comparison calculations are processed.

Now, as shown in FIG. 7, the surface to be ground 14a of the magnetic head 14 during the grinding process and the grinding surface 18a of the grinding wheel 18 have an inclination angle of θ (that is, the traverse axis and the surface before the grinding process Suppose that the grinding process is performed in a state in which the magnetic head and the surface to be ground 14a have an inclination angle of θ), then l _L ≠ l _R , and the center span of both resistors 32L and 32R is When l ₀ , θ is determined by the following equation.

θ=tan ^-1 (1l _L -l _R |/l ₀ ) ... θ calculated by the above formula is the processing system CPU2
9, and based on _this calculated value of θ, the motor 6 shown in _FIG . If it is rotated by the above θ in the direction of CCW in Fig. 7, l _L will be
Grinding can be performed with the angle corrected so that = l _R.

In this way, both resistors 32L, 3 are used during grinding.
By constantly measuring the resistance values R′ _L and R′ _R of 2R, if there is a difference between R′ _L and R′ _R (that is, if there is a difference in the total length of both resistors), the rotary table 5, the grinding process can be performed in such a state that the total lengths l _L and l _R of both resistors always satisfy l _L = l _R for each traverse. Therefore, both resistors 32
The gap depth of the tracks arranged between L and 32R can be ground uniformly for each track with high precision, and the absolute amount can also be ground with high precision.

In operation 4, the above-described grinding cycle is repeated, and the resistance values of both the resistors 32L and 32R are
When R′ _L and R′ _R reach a predetermined resistance value, the grinding cycle is finished, and then the magnetic head 14 is moved at the measurement machining origin by the X-axis drive table 1 and Y-axis drive table 3, and the grinding Rotation of the grindstone 18,
The swinging motion of the work holder 12 is stopped, and the operation is completed. At this time, all grinding data such as the final grinding position and the final resistance values of both resistors are recorded on the floppy disk stored in the processing system floppy disk drive 31, and some of them are basic data for the next grinding process. It is used as a.

FIG. 8 shows a flowchart of the grinding cycle.

The flowchart shown here can be easily modified by changing the grinding program.

By the way, when correcting the angle of the magnetic head in operation 4, there are two problems: variation in the resistance value of the resistor due to heat generated on the machined surface during grinding, and variation in the absolute position in the cutting direction due to angle correction. , the following considerations have been made for these. First, regarding the former, when the traverse movement is completed during the grinding process and the magnetic head 14 is at the grinding process start and end positions (shown in FIG. ), the majority measurement method involves measuring the resistance values R′ _L and R′ _R of both resistors n times and adopting the measured value with the largest number of measured values, or until the measured values become stable. By using a continuous comparison measurement method that continues measurement and adopts the measured value at a stable point, it is possible to prevent measurement errors caused by fluctuations in the resistance value of the resistor due to heat generation on the machined surface during grinding. .

Regarding the latter, for example, as shown in Figure 9,
End the traversal at that point in state (A),
When the angle is corrected for state (B) at the start and end positions of the grinding process, ΔY in the cutting direction (Y-axis direction)
Since the absolute position of the magnetic head ground surface 14a moves by the same amount, if the same depth of cut is made and the next traverse is started, one end of the magnetic head ground surface 14a will be cut an extra amount of ΔY. In contrast, the relative position between the center of the pivot rotation axis 9, which is the center of rotation during angle correction, and the work holder 12, which fixes the magnetic head 14, is determined in advance by the processing system.
It is input to the CPU 29, and the magnetic head 1
4 is positioned and fixed to the work holder 12 with high precision on a plane basis, and the absolute angular position with respect to the pivot rotation axis 9 is determined by the motor 6.
The absolute position of the magnetic head 14 with respect to the center of the pivot rotation axis 9 can be constantly calculated and managed by the processing system CPU 29 because it is constantly input to the processing system CPU 29 by a rotary encoder (not shown) disposed on the rotation axis of the magnetic head 14. Therefore, the fluctuation ΔY in the absolute position in the cutting direction due to angle correction can be calculated and processed by the processing system CPU 29. Therefore, if the processing system CPU 29 determines the cutting position during the next traverse by taking into account the fluctuation ΔY in the absolute position in the cutting direction due to the angle correction, an additional cut by ΔY will not be made during the next traverse.
Furthermore, during the above-mentioned angle correction, the absolute position variation in the traverse direction (X-axis direction) is accompanied by the variation ΔY in the absolute position in the cutting direction, but this variation is caused by the variation in the traverse range of the magnetic head 14 with respect to the grinding wheel 18. Can be ignored with appropriate settings.

Note that the supply of grinding fluid can be automatically controlled by using a solenoid valve.

In addition, in this text, we have described a cylindrical grinder that performs grinding with a single magnetic head, which is the object to be ground, but even when multiple magnetic heads are installed, the above-mentioned operations 1 to 4 are repeated. This enables continuous and automatically controlled cylindrical processing.

<Effects of the Invention> As explained above, according to the cylindrical grinder according to the present invention, by determining the amount of displacement of both ends of the surface to be ground of the magnetic head before cylindrical grinding, the distance between the surface to be ground and the traverse axis can be determined. The parallelism of the magnetic head is determined, and the position of the magnetic head is adjusted using the Y-axis moving table and rotary table until the parallelism of both is below the allowable value. The amount of grinding of the magnetic head is determined by constantly measuring the resistance value of the resistor, and the inclination of the surface to be ground determined from this amount of grinding is determined by rotating the rotary table and moving the Y-axis moving table. Since the gap depth of each track of the ground magnetic head is highly uniform, it is not affected by dimensional variations due to wear of the grinding wheel or thermal expansion of the workpiece due to heat generated during grinding. Accurate cylindrical grinding of magnetic heads is possible.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of the main body of the machine, where A and A' are the grinding cycle start positions, B is the measurement/processing origin position, C is the stylus contact position of the electric micrometer probe of the magnetic head, and D is the start of the grinding process. Fig. 2 is a system configuration diagram, Fig. 3 is an overview flowchart of the operating sequence of the system, and Fig. 4 is a measurement of parallelism and angle of the magnetic head grinding surface using an electric micrometer. An enlarged view of the main parts related to correction, Figure 5 is a flowchart regarding parallelism measurement and angle correction of the magnetic head grinding surface using an electric micrometer, Figure 6 is a configuration diagram of the gap part of the magnetic head, and Figure 7 is magnetic head grinding. FIG. 8 is a flowchart for grinding the magnetic head, and FIG. 9 is an enlarged view of the main part regarding the variation in the absolute position in the cutting direction due to angle correction. DESCRIPTION OF SYMBOLS 1...X-axis drive table, 3...Y-axis drive table, 5...Rotary table, 14...Magnetic head, 15...Electric micrometer probe, 18
... Grinding wheel, 29 ... Processing system CPU, 31 ...
floppy disk drive.

Claims (1)

[Scope of Claims] 1. Measuring means for measuring the amount of displacement perpendicular to the traverse axis at both ends of the surface to be ground of the magnetic head in the traverse axis direction; A resistor having a predetermined resistance value that is pre-installed on the magnetic head to measure the amount of grinding; a Y-axis moving table that is movable in parallel in a direction perpendicular to the traverse axis; and a Y-axis moving table that is the same as the Y-axis moving table. A rotary table rotatable within a plane, and parallelism detection for determining the parallelism of the surface to be ground of the magnetic head with the traverse axis based on the amount of displacement determined by the measuring means before cylindrical grinding. and a surface-to-be-ground setting means for making the surface to be ground of the magnetic head parallel to the traverse axis by rotating the rotary table based on the parallelism before cylindrical grinding. , a resistance value measuring means for constantly measuring the resistance value of the resistor during cylindrical grinding, and determining a grinding amount from the resistance value determined by the resistance value measuring means during cylindrical grinding, and calculating from the grinding amount. a tilt angle detection means for determining the tilt angle of the surface to be ground of the magnetic head; and a tilt angle detection means for determining the tilt angle of the surface to be ground of the magnetic head; While canceling the tilt angle, the Y
position correction means for correcting the absolute position of the magnetic head by moving the axis movement table; and cylindrical grinding when the resistance value determined by the resistance value detection means reaches a predetermined value. A cylindrical grinding machine characterized by comprising a grinding finishing means for finishing grinding.