JPH0446766A - Method and device for dressing grinding wheel in surface grinding process - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a surface grinding process using a surface grinding device.
The present invention relates to a dressing method that allows a grindstone to stand on its own efficiently, and a dressing device for implementing the method.

[Conventional technology]

As shown in Fig. 8, the surface grinding device has a saddle i that is movable in the front and back direction placed on the front part of the machine base, and is mounted on the saddle i in a direction perpendicular to the moving direction of the saddle i (in the figure, A table j movable in the horizontal direction) is stacked on top of the other, and a magnetic chuck a is fixed on the top surface of the table j. The workpiece b is machined by magnetically attaching the workpiece b.

Incidentally, in the surface grinding process, there is a process of making a disc-shaped grindstone with a hollow surface stand on its own, that is, a dressing process, and conventionally, this dressing is performed as follows.

FIGS. 7A to 7F are explanatory diagrams showing this process. Figure 7 (a) shows a state in which a workpiece magnetically attached to a magnetic chuck a is being ground by a disc-shaped grindstone C, and the dressing of the grindstone C, that is, the self-standing state, is in the middle of grinding. This is done when the grinding effect of the grinding wheel C has become significant and the grinding effect has decreased. The dresser shown as d in the figure is constructed by protruding from the upper end face f of a truncated conical pedestal e having a constant height and a dresser head g having a diamond tip attached to its tip. And when the need for independence arises,
This dresser d is attached to the magnetic chuck a on the side of the workpiece.
The magnetic chuck a is moved horizontally by moving the table j horizontally, and the surface of the grindstone is ground by bringing the rotating grindstone into contact with the dresser head g. Rad to the dresser to the surface of the whetstone
To position the grindstone, first move the magnetic chuck a horizontally by moving the table j, position the dresser d below the grindstone (Fig. 7 (b)), and then move the grindstone C.
is lowered to bring the surface of the grindstone into contact with the dresser head g. Note that the contact between the grindstone C and the dresser gear g is confirmed by the phenomenon of ignition from the rotating grindstone.

Next, after grinding to a certain depth from the surface of the grindstone to complete self-support, the grindstone C is moved upward once, and the magnetic chuck a is moved horizontally to position the workpiece B below the grindstone.
After lowering the grindstone C until it comes into contact with the workpiece b, grinding of the workpiece b is resumed (Fig. 7 (c), (d), (e)).
. By the way, in the above process, if the height position of the dresser head g and the top surface height position of the workpiece b match,
Although the vertical movement of the grindstone C is no longer necessary, since there are actually countless types of workpieces b, the height position of the top surface thereof is not constant, and therefore, the vertical movement of the grindstone C cannot be eliminated.

[Problem to be solved by the invention]

However, moving the grinding wheel C up and down in the above method is not only troublesome, but also because popular surface grinding machines that do not use numerical control do not have a means to measure and display the amount of vertical movement of the grinding wheel. The amount of movement involved was nothing compared to the experience and intuition of the operator, and the work required a level of skill. Also, when returning workpiece B to the lower part of the grindstone, if you forget to move the grindstone C upward or the amount of upward movement is insufficient, the grindstone C may collide with workpiece B and damage it, or the workpiece may be thrown off. It was also extremely dangerous.

The present invention has been made in view of the current situation, and it is possible to position the workpiece and dresser directly under the grinding wheel without relying on the experience or intuition of the operator.
It is an object of the present invention to provide a dressing method that can completely prevent a grindstone from colliding with a workpiece and also simplify the surface grinding process, and a dressing device for realizing the method.

[Means to solve problems]

The inventor of the present invention came up with the idea that in order to solve the above problem, it would be sufficient to eliminate the vertical movement of the grinding wheel, and positioned the workpiece and dresser directly below the grinding wheel, which is necessary when transitioning between the grinding process and the dressing process. We proposed that this can be done basically only by the horizontal movement of a magnetic chuck.

In other words, the dresser used is one in which the height of the tip of the dresser head matches the height of the top surface of the workpiece, and the height of the workpiece and dresser directly below the grinding wheel, which is necessary when transitioning between the grinding process and the dressing process, is used. The positioning is shown in Figure 1 (a).

As shown in (b) and (c), it was proposed to basically perform the grinding only by the horizontal movement of the magnetic chuck a, eliminating the vertical movement of the grinding wheel C.

In order to make this method applicable to various workpieces with different heights, the height position of the dresser head needs to be variable. We have developed a dresser in which the upper end surface of the pedestal along which the dresser head protrudes can be raised and lowered manually or automatically.

Also, as mentioned above, it is necessary to match the height position of the dresser head with the height position of the top surface of the workpiece, but it is also necessary to make the height position of the dresser head match the height position of the top surface of the workpiece after raising and lowering. In order to know this, it is essential to measure the height position of the dresser head. However, the tip of the dresser head is extremely small and difficult to measure directly. Therefore, instead of directly measuring the height position of the tip of the dresser head, the present inventor fitted a metal cap with a flat top surface onto the dresser head and measured the height position of the top surface of this metal cap. By doing this, we decided to indirectly detect the height position of the dresser head. If a metal cap is fitted onto the dresser head, the height of its top surface will be at least higher than the height of the end of the dresser, so the height of the tip of the dresser head and the height of the top surface of the workpiece can be adjusted. If the matching operation is to be performed using the top surface of the metal cap as a reference, it will be necessary to arrange a raising member on the top surface of the workpiece as well.

The gist of the method of the present invention based on such an idea is to construct a dresser in which a head serving as a grinding blade is protruded from the upper end surface of the pedestal body, and the upper end surface can be raised and lowered, and the dresser is used as a workpiece. It is placed on a magnetic chuck on the side, and a metal cap with a flat top and an inner space that can accommodate a protruding dresser head is fitted on the upper end surface of the workpiece. is a metal block having a height equal to the height of the single metal camp minus a distance corresponding to the protruding height from the upper end surface of the pedestal of the dresser head, and whose top surface is a flat surface. At the same time, the workpiece on which the metal block is placed is positioned below the detection head of the distance sensor, and the distance to the top surface of the metal block is measured and the data is stored, or the separation distance is a preset distance. The distance sensor is moved up and down so that The height of the dresser is determined by raising and lowering it to match the distance between the top surface of the metal block and the detection head, and the workpiece and dresser are placed directly under the grinding wheel, which is necessary when transitioning between the grinding process and the dressing process. This feature is characterized in that the positioning of the magnetic chuck is performed only by the horizontal movement of the magnetic chuck.

The dressing operation, which is the second invention that makes such a method possible, includes a dresser in which a head serving as a grinding blade is formed protrudingly on the upper end surface of a pedestal whose upper end surface is movable up and down;
A metal cap having an internal space into which the dresser head can be fitted and whose top surface is flat, and the height of the metal cap alone corresponds to the protrusion height of the tip of the dresser head from the upper end surface of the pedestal. a metal block placed on the top surface of the workpiece, the metal block having a height minus the distance corresponding to the height of the workpiece and having a flat top surface, and positioned above the height position of the dresser head and the top surface position of the workpiece; A distance sensor that can continuously measure the distance to an object or can set the sensing distance of the object in advance and sends out a notification signal when the object reaches the set distance; It is an object of the present invention to provide a dressing device comprising an arithmetic processing unit that processes notification signals sent from the operator, and notification means that notifies the operator of the calculation results.

[Effect]

In the dressing method and dressing work of the present invention, a metal cap is fitted onto a dresser magnetically attached to a magnetic chuck, a metal block is placed on the upper surface of the workpiece, and a distance sensor is used to attach a metal cap to the dresser. The height positions of the top surface of the cap and the top surface of the metal block are made to match each other, and as a result, the height position of the dresser head is made to match the height position of the top surface of the workpiece. When the need arises during surface grinding work,
By horizontally moving only the magnetic chuck while keeping the height of the grindstone fixed, the dresser is positioned directly below the grindstone, and the dresser head is brought into contact with the surface of the grindstone. According to this method, the transition between the grinding work and the dressing work can be performed only by horizontal movement of the magnetic chuck, making it possible to improve the efficiency of the dressing work. No experience is required.

〔Example〕

Next, details of the present invention will be explained based on illustrated embodiments.

What is shown in FIGS. 2(A) and 2(B) is an embodiment of a dresser newly developed to enable the method of the present invention. This dresser is characterized by making the height position of the dresser head variable, whereas conventional dressers had a fixed height position. For example, as shown in the illustration, this dresser 1
, a lifting platform 2b is mounted on a truncated conical pedestal main body 2a, a male screw 3 is screwed on the upper outer peripheral surface of the pedestal main body 2a, and an annular dial 4 is screwed on the inner peripheral surface with a female screw (not shown). The pedestal 2 is configured by attaching the pedestal 2 so as to be movable up and down through a threaded relationship.
A dresser head 7 having a diamond tip 6 attached to the tip thereof is protruded from the upper end surface 5 of the dresser head 7. In order to prevent the dresser blade 7 from digging into the surface of the grindstone, it is configured to be inclined so that it can escape with respect to the direction of rotation of the grindstone.

In the illustrated example, a threaded engagement between a male screw and a female screw is used as the elevating mechanism of the dresser 1, and the elevating and lowering of the dresser head 7 is performed by manually rotating the annular dial 4, but the elevating mechanism is It is also possible to use other devices, for example, a drive source such as a servo motor may be incorporated, and the dresser head 7 may be moved up and down by the drive force of the motor. In addition, since the height of the dresser head 7 in the illustrated example is detected by the method described later, the annular dial 4
It is not necessary to have a scale, but a scale may be provided so that the approximate elevation distance can be grasped visually.

The mark marked on the bottom of the base body 2a of the dresser 1 is
This is a matching mark used for positioning when magnetically attaching the dresser 1 to the magnetic chuck, and a △ mark is printed on the magnetic chuck in correspondence with the mark.

What is shown in FIG. 3 is an explanatory view of a main part showing one embodiment of the method of the present invention using the dresser having the above structure. 8 in the diagram
1 is a workpiece, and 1 in the figure is the aforementioned dresser. The method of the present invention matches the height of the top surface of the workpiece with the height of the tip of the dresser head, and places the workpiece 8 directly below the grinding wheel.
The positioning work of the dresser 1 is basically performed only by the horizontal movement of the magnetic chuck 9. Figure 3 shows the workpiece top surface height D in this series of operations.
This figure shows the process of matching l with the height D2 of the tip of the dresser head.

A dresser 1 is magnetically attached to a side position of a workpiece 8 that is magnetically attached to a magnetic chuck 9, and a cylindrical metal cap 10 is fitted onto the upper end surface 5 of a pedestal 2 of the dresser 10. The dresser 1 is magnetically attached to the upper surface of the magnetic chuck 9 by aligning the mark on the dresser 1 side with the Δ mark marked on the upper surface of the magnetic chuck 9. Further, the metal cap 10 has a flat top surface 11.
It has an internal space in which the dresser head 7 can be housed, and is made of a non-ferrous metal such as stainless steel. The upper surface of the workpiece 8 has a height d3 (d3
=dl-d2) is placed on the metal block 12. The metal block may be either hollow or solid, and like the metal cap 10, it may have a cylindrical shape with a lid.

Like the metal cap 10, the metal block 12 is made of a non-ferrous metal such as stainless steel, and its top surface 13 is a flat surface.

The reason why the metal cap 10 is fitted onto the dresser head 7 is because there is no means to directly observe the minute tip of the dresser head.
is used as the detection surface, and by measuring the distance to the top surface 11, the height position of the dresser hend door is indirectly measured.On the other hand, a metal block 12 is placed on the top surface of the workpiece. The height position of the top surface of the metal block 120 is connected to the metal cap 10 fitted onto the dresser 1.
This is to indirectly realize the fundamental idea of the present invention, which is to match the top surface positions of the dresser head 7 and the workpiece 8 by matching the height position of the top surface 11 of the dresser head 7 and the workpiece 8.

Top surface 11 of metal cap 10 and metal block 12
The reason why the top surface 13 is made flat is to enable observation with a sensor, and the area of the top surface is appropriately set according to the sensitivity of the sensor.

What is shown as 14 in the figure is a detection head of a distance sensor, and notification means such as a lamp and a buzzer are connected to the distance sensor, and when the distance between the detection head 14 and the object reaches a predetermined distance, The notification means is configured to operate. In this embodiment, a high-frequency oscillation type proximity sensor that is sensitive to stainless steel, which is the material of the metal cap 10 and the metal block 12, and is compatible with non-ferrous metals is used as the distance sensor. By using a distance sensor compatible with non-ferrous metals, it is no longer affected by ferrous members such as the workpiece 8, dresser 1, or even the magnetic chuck 9.
Moreover, the influence of iron powder scattered by grinding can also be eliminated. Optical and ultrasonic types can also be used as distance sensors, but optical types tend to malfunction if oil or water adheres to the work surface, and ultrasonic types require larger devices. For these reasons, it is preferable to use a high frequency oscillation type distance sensor. Note that if the height positions of the top surfaces of the metal cap IO and the metal block 12 are optically separated from iron members such as the work 8 and the dresser 1, it is also possible to use an iron-compatible magnetic sensor. In addition, the distance sensor used in this example was a proximity sensor that sends out a detection signal when the distance between the detection target and the sensor reached a predetermined distance. It is also possible to use a proper distance sensor that can continuously detect changes.

Such a group of devices is installed on the magnetic chuck 9, but the magnetic chuck 9 itself is fixed on a table 24 as shown in FIG. The table 24 is provided so as to be slidable in a direction perpendicular to the sliding direction of the saddle 23 on a saddle 23 that is slidably placed on the machine base 22, and the saddle 23 and the table 24 are independently arranged. By horizontal movement, the workpiece 8 and the dresser 1 magnetically attached to the magnetic chuck 9 are guided to the lower part of the grindstone. The dresser 1 is removed from the magnetic chuck 9 when not dressing, and the magnetic chuck 9 is removed when dressing.
However, if the magnetic attachment position changes each time, the positioning of the dresser 1 below the grindstone must be visually adjusted each time, which is extremely complicated. In this embodiment, in order to solve this problem, as shown in FIG.
and a locking mechanism 2 for defining the locking position between the table 24 and the table 24.
5 was proposed. The locking mechanism 25 is composed of a stopper 25a fixed to the upper surface of the saddle 23 and a receiver 25b fixed to the side surface of the table 24, details of which are shown in FIG.
It is shown in (a) and (b). The stopper 25a has a pin 28 having a tapered head 26 at the tip and a grip 27 at the base end, which is slidably inserted into a support 29 vertically fixed to the upper surface of the saddle 23 in the thickness direction of the support 29. By rotating the grip, the position of the pin 28 that has moved back and forth can be fixed.

On the other hand, the receiver attached to the side of the table 24 is the fixture 25b.
The recess 30 is formed into which the head 26 of the pin 28 can be fitted. As a locking mechanism, the table 24
It is also possible to adopt other configurations as long as the positional relationship between the saddle 23 and the saddle 23 can be defined.

The work of matching the height positions of the metal cap top surface 11 and the metal prong top surface 13 is performed as follows. First of all,
The magnetic chuck 9 is moved horizontally, the workpiece 8 on which the metal block 12 is placed is moved horizontally, and the metal block 12 is placed at a position below the detection head 14. In this state, when the detection head 14 is lowered to shorten the distance d4 between the detection head 14 and the top surface of the metal block, the distance d4 is set to the distance preset in the proximity sensor, for example 10+a+
Since a notification means such as a lamp or a buzzer is activated when the time reaches n, the lowering of the detection head 14 is stopped after confirming this.

Next, by moving the table 24, the magnetic chuck 9 is horizontally moved, and the dresser 1 with the metal cap 10 fitted thereon is moved to place the metal cap 10 below the detection head 14. is turned to move the lifting platform 2b upward until the distance between the metal cap top surface 11 and the detection head 14 reaches a preset distance. Similarly to the above, the operator is notified by notification means such as a lamp or a buzzer whether the distance between the metal cap top surface 11 and the detection hem 114 has reached a predetermined distance. By simply stopping the rotation of the annular dial 4, the respective height positions of the metal cap top surface 11 and the metal block top surface 13 can be made to match, and as a result, the height position of the top surface of the workpiece and the tip of the dresser head can be made to match. The positions can be matched. The height of the dresser head does not need to be readjusted as long as the workpiece to be ground is of the same standard, but it must be readjusted when the standard of the workpiece changes.

In addition, since the height position of the dresser head 7 is made to match the height position of the upper surface of the workpiece 8, the workpiece 8 to be used
The height position of the dresser head 7 slightly fluctuates up and down depending on whether it is before or after grinding. If a pre-grinded workpiece is used as a standard for height setting, the height of the dresser head will be set higher, and if a grounded workpiece is used as a reference workpiece, it will be set lower. It will be done. Therefore, it is necessary to take this into consideration when deciding whether to use the reference work before grinding or after grinding. Note that it is also possible to use a test piece having the same shape as the workpiece instead of using the actual workpiece as the reference workpiece.

FIG. 6 shows an embodiment in which the above-described dresser head height setting device is incorporated into a surface grinding machine.

In the figure, 15 is a disk-shaped grindstone, 16 is a casing that encases the grindstone 15, and 17 is a grinding fluid supply path. 18 moves up and down in conjunction with the up and down movement of the grindstone 15 ii! A detection head 14 of a proximity sensor is attached to the tip of an arm 19 extending downward from the mounting table 18, and on the other hand, a signal sent from the detection head 14 is processed on the mounting table. An arithmetic processing unit 20 is installed for this purpose. or,
A digital meter 21 that digitally displays the amount of descent of the grindstone 15 is installed on the side of the arithmetic processing unit 20. The digital meter 21 is equipped as standard on a numerically controlled surface grinding machine, and when the grinding wheel 15 comes into contact with the workpiece 8 or the dresser head 7, the reset switch is pressed to display zero, and the meter 21 is set to zero from the height position. It is provided to digitally display the amount of cutting of the workpiece or grindstone by digitally displaying the amount of vertical displacement.

The method of using the surface grinding machine having such a configuration is as follows. First, the reference work 8 and the dresser 1 are magnetically attached to the magnetic chuck 9, the metal block 12 is placed on the work, and the metal cap 10 is externally fitted to the J dresser 1. horizontally move the workpiece 8 and the dresser 1, position the metal block 12 directly under the detection head 14, and remove the grindstone 15.
and lower the detection head 14. As the detection head 14 continues to descend, when the distance between the detection head 14 and the top surface of the metal block reaches a pre-registered distance, for example 10 meters, a notification means such as a lamp or buzzer will be activated. After confirming this, stop the descent of the grindstone at step 15. Next, the magnetic chuck 9 is moved horizontally to position the metal cap 10 directly below the detection head, and the annular dial 4 is turned to raise the metal cap 10, setting the distance to the detection head 14 to be 10 degrees. do. Since the notification means is activated when the distance from the detection head 14 reaches 10 mm, adjustment of the annular dial 4 is easy. Once the height of the dresser head has been set in this way, the actual workpiece to be ground is magnetically attached to the magnetic chuck, and the grindstone is lowered to begin grinding the workpiece. When the grinding wheel needs to stand on its own during grinding, the magnetic chuck 9
The grindstone 15 is made to stand on its own by horizontally moving the dresser 1 to position it directly below the grindstone and bringing the dresser head 7 into contact with the surface of the grindstone. The height-adjusted dresser 1 must be removed from above the magnetic chuck 9 when grinding the workpiece 8, and when dressing is required, it must be magnetically attached again to the magnetic chuck 9 to accurately position the dresser 1 below the grindstone. However, in this embodiment, this work involves magnetically attaching the dresser 1 to the table 24 so that the mark on the dresser 1 and the △ mark on the magnetic chuck 9 match, and moving the table 24 to align the bottle head of the stopper 25a. The portion 26 can be fitted by simply fitting it into the tool 25b. By doing this, it becomes possible to easily and accurately position the dresser head directly under the grindstone at any time, so that there is no need for fine training to position the dresser head directly below the grindstone.

In addition, the distance d5 between the detection head 14 and the lowest part of the grinding wheel is
If the distance is set to be the sum of the height d3 of the metal block alone and the sensitive distance d4 of the detection head 14, as in the case of turning the block, after completing the setting work of the height position of the dresser head 7, It is possible to bring the dresser head 7 into contact with the grindstone 14 simply by horizontally moving the chuck 9, and there is basically no need to move the grindstone up and down. In particular, if the digital meter 21 is reset to zero display at the same time as setting the height position of the dresser head 7, the subsequent vertical fluctuations of the grinding wheel 15 will be digitally displayed. The amount can be easily determined.

〔Effect of the invention〕

The dressing method and device for a grindstone in a surface grinding process of the present invention as described above constitutes a dresser in which the height position of the dresser head can be adjusted. A dresser head is placed on the workpiece, and the distance from the detection head of the distance sensor to the top of the metal cap matches the distance between the detection head and the top of the metal block. The height position of the workpiece is made to match the height position of the top surface of the workpiece, and when it becomes necessary to stand up on its own during the grinding process, the dresser head can be brought into contact with the grinding wheel by horizontally moving the magnetic chuck and the stand-up can be done. Moreover, after dressing is completed, the grinding wheel is returned to the top surface of the workpiece by simply moving the magnetic chuck horizontally, so there is no need to move the grinding wheel up and down, greatly simplifying the dressing work, and eliminating the need for dressing work as in the past. This eliminates the need for proficiency. In addition, since there is basically no need to move the grindstone up and down,
There is no longer an accident that occurs in the past, where a dresser or workpiece collides with a grindstone that has been forgotten to be lifted, resulting in damage to the grindstone.

In addition, a proximity sensor is used as a distance sensor, and the detection head of the proximity sensor is raised integrally with the grindstone by 4 degrees, and the detection head is installed at a position close to the height of the single metal block from the bottom of the grindstone. If the height position of the dresser head is set and the height position of the dresser head is set, then there is no need to readjust the height of the grinding wheel when moving to grinding work. Grinding work can be resumed immediately by simply moving the magnetic chuck horizontally. Moreover, in the case of surface grinding equipment equipped with a digital meter,
When the height position of the dresser head is determined, if it is reset to zero display, the amount of vertical displacement of the grinding wheel thereafter is displayed digitally, so the amount of cutting of the workpiece and the grinding wheel can be easily grasped.

Additionally, when stainless steel is used as the material for the metal cap and metal block, and a high-frequency oscillation type sensor compatible with non-ferrous metals is used as the proximity sensor, the surface condition of the workpiece and the presence of grinding debris may affect the measurement results. Highly accurate measurement is possible without giving any

[Brief explanation of drawings]

FIGS. 1(a), (b), and (c) are explanatory diagrams showing the basic idea of the present invention, and FIG. 2(a) is a front view showing one embodiment of the dresser used in the present invention. Fig. 2 (b) is a front view showing the dresser with the lifting platform raised, Fig. 3 is an explanatory diagram showing the method of adjusting the height position of the dresser head in the present invention, and Fig. 4 is a view of the table and saddle. An explanatory diagram showing the locking mechanism, FIG. 5(A) is a perspective view showing the main parts of the locking mechanism, FIG. 5(B) is a plan view of the same, and FIG. 6 is surface grinding using the method of the present invention. Explanatory drawings showing the main parts of the machine, FIGS. 7 and 8, are conventional examples. It is. I: Dresser 2: Pedestal, 3: Male screw, 4: Annular dial, 5: Upper end surface, 6: Diamond tip, 7: Dresser head, 8: Workpiece, 9: Magnetic chuck, 10
: Metal cap, top surface at l, 12: metal block, 13: top surface, 14: detection head, 15: grindstone, 16: casing, 182 mounting table, 20: arithmetic processing section, 22: machine stand, 24: table, 26: head, 28: pin, 30: recess. 17: grinding fluid supply path, 19: arm, 21: digital meter, 23: saddle, 25: locking mechanism, 27: grip, 29: strut,

Claims (1)

[Claims] 1) For a workpiece placed on a magnetic chuck,
A disc-shaped grindstone is lowered into contact with the workpiece to grind the top surface of the workpiece, and when the grindstone is overturned, the grindstone is removed from the workpiece and comes into contact with the head of a dresser placed on the magnetic chuck on the side of the workpiece. Let them become independent,
After the grindstone has become self-supporting, the grindstone is returned to the workpiece grinding position and grinding is resumed.In the dressing process of the grindstone in the surface grinding process, a head serving as a grinding blade is provided protruding from the upper end surface of the pedestal body, and the upper end surface is movable up and down. The dresser is placed on a magnetic chuck on the side of the workpiece, and the upper end surface thereof has an internal space in which a protruding dresser head can be housed, and the top surface is a flat metal surface. A metal cap is fitted onto the top surface of the other workpiece, and the top surface of the metal cap has a height equal to the height of the metal cap itself minus a distance corresponding to the protrusion height from the top end surface of the pedestal of the dresser head. A metal block with a flat surface is placed, and the workpiece with the metal block placed on it is positioned below the detection head of the distance sensor, the distance to the top of the metal block is measured, and the data is collected. The distance sensor is moved up and down so that the distance is memorized or the separation distance becomes the preset distance, and then the magnetic chuck is moved horizontally and the dresser with the metal cap fitted is positioned below the detection head and the top of the metal cap is moved. The distance to the surface is measured, and the height is determined by raising and lowering the dresser so that this distance matches the distance between the top surface of the metal block and the detection head, and the transition between the grinding process and the dressing process is achieved. A dressing method for a grinding wheel in a surface grinding process in which the positioning of the workpiece and dresser directly below the grinding wheel, which is sometimes necessary, is performed only by the horizontal movement of a magnetic chuck. 2) A dresser in which a head serving as a grinding blade is formed protruding from the upper end surface of a pedestal whose upper end surface can be raised and lowered, and a metal member having an internal space into which the dresser head can be fitted and whose top surface is flat. and a top surface of the workpiece having a height obtained by subtracting a distance corresponding to the protruding height of the tip of the dresser head from the top end surface of the pedestal from the height of the metal cap alone, and whose top surface is a flat surface. The metal block placed on the dresser head is positioned above the height of the dresser head and the top surface of the workpiece, and the distance to the object can be measured continuously or the sensing distance of the object can be set in advance. a distance sensor that sends out a notification signal when the target object reaches a set distance; a calculation processing unit that processes the distance data detected by the distance sensor or the notification signal sent from the distance sensor; A dressing device for a grindstone in a surface grinding process, comprising: a notification means for notifying the user; and a dressing device for a grindstone in a surface grinding process. 3) In addition to using a proximity sensor as a distance sensor, the detection head of the proximity sensor is configured to move up and down integrally with the grinding wheel, and the mounting position of the detection head is close to the height of the single metal block with respect to the bottom of the grinding wheel. The method for dressing a grindstone in a surface grinding process according to claim 1, or the dressing device according to claim 2, wherein the position is displaced upward by a distance added to the sensitive distance of the sensor. 4) The surface grinding process according to claim 1, wherein stainless steel is used as the material for the metal cap and the metal block, and the distance sensor is of a high frequency oscillation type and compatible with non-ferrous metals. or the dressing device according to item 2.