JP2639811B2 - Discharge forming method of blade edge - Google Patents

Description

The present invention relates to a method for performing dressing of a blade by electric discharge formation.

[Conventional technology]

Ultra-thin blades are widely used for grooving and cutting of magnetic heads and the like. High precision is required for this type of processing, so if the blade edge wears out and the blade edge shape is deformed, it is necessary to immediately dress it and restore the blade edge shape to the original correct shape. is there.

This type of blade is generally formed by an electrodeposition method (plating method) and has conductivity, and the method shown in FIG. 8 is known as a method of forming this blade edge. In this method, a dresser (for example, a green carborundum grindstone) 2 is fixed to the tip of a spindle 1 that can move forward and backward, and for example, is rotated at a high speed in an oblique direction with respect to a rotary blade (grindstone) 3 for grinding. Press the dresser 2 to scrape off the shaded area A, then rotate the spindle 1 by φ to press the dresser 2 from the opposite diagonal direction,
Similarly, by shaving off the shaded portion B, the cutting edge of the blade 3 is formed into, for example, a V-shape.

[Problems to be solved by the invention]

However, the conventional method described above requires
Since it is necessary to secure a space for rotating the spindle 1 by φ, the size of the apparatus becomes large, and it becomes difficult to incorporate this cutting edge forming apparatus (dresser) into a grinding apparatus such as a dicing apparatus. It had to be formed as a separate unit.

For this reason, when forming (dressing) the cutting edge of the blade, it is necessary to remove the blade from the grinding device and attach the removed blade to the forming device for the cutting edge, which makes the operation complicated. there were.

Further, as described above, since the formation (dressing) of the cutting edge is performed by removing it from the grinding device, when the processed blade is mounted on the spindle of the grinding device again, the positional displacement of the blade is likely to occur. There is a problem that it has a bad effect on

Further, since the blade is formed while the blade is pressed by the dresser, the blade is easily processed in a bent state, which hinders accurate formation of the blade.

In order to solve the above-mentioned various problems, the present inventor has proposed a method of forming a cutting edge of a cutting edge by electric discharge using conductivity of a blade.

In this proposed method, as shown in FIG. 7, for example, the wall surfaces 7a and 7b of the electrode 6 having a V-shaped groove corresponding to the blade edge surface of the blade having a V-shaped cross section are used. It is arranged so as to face the surfaces 3a and 3b, and while supplying an electric discharge machining liquid such as water between the electrode 6 and the blade 3,
A discharge voltage is applied between the two and the cutting edges 3a and 3b are simultaneously formed by the discharge between the two.

According to the proposed method, since the electrode 6 can be formed in a small size, the electrode 6 can be suction-fixed on the chuck table of the grinding device, and without removing the blade 3 from the grinding device.
In addition, since the cutting edge can be formed in a non-contact state with the blade 3, this greatly contributes to solving the above-mentioned conventional problems.

However, on the other hand, this proposed method has a blade 3
Since the cutting edge surfaces 3a and 3b are formed simultaneously, the cutting edge surfaces
At the time of simultaneous discharge of 3a and 3b, the V-shaped peak 9 has the highest discharge energy. Therefore, since the shaving allowance due to the discharge of the pointed head 9 is larger than the shaving allowance of the both surfaces 3a and 3b, the pointed head 9 may form a rounded and sharp V-shaped cutting blade. A new problem of not being able to do so has arisen.

The present invention has been made in view of the above circumstances, and its object is not limited to a V-shape, and the cutting surface of a blade having a pointed protrusion is sharpened without the pointed head being rounded. An object of the present invention is to provide a method for forming a discharge of a blade edge capable of forming a discharge.

[Means for solving the problem]

The present invention is configured as follows to achieve the above object. That is, a first aspect of the present invention is a method for forming an electric discharge of a blade cutting edge having a multifaceted cutting edge having a pointed protruding portion, wherein an electrode having a female wall surface corresponding to each cutting edge of the blade cutting edge is provided. Prepare it in advance and use its female 1
One wall is relatively formed closer to the blade edge surface of the corresponding blade, and one surface is formed by electric discharge. After the completion of the discharge formation, the next female wall surface is relatively closer to the blade edge surface of the corresponding blade and the next is formed. As in the case of discharge-forming the blade tip surface, the blade tip surface of the blade is sequentially discharged-formed for each surface, and then each of the discharge-formed blade tip surfaces is rubbed against the grindstone surface to discharge the discharge deposits during the discharge formation from the blade tip surface. It is configured to be removed.

[Action]

According to the first aspect of the present invention, the discharge formation of the blade cutting edge having the multi-faceted cutting surface is performed by disposing the female electrode wall corresponding to each surface of the cutting edge to the cutting surface. The discharge formation of the next cutting edge is always performed after the discharge formation of one cutting edge is completed. Therefore, since the cutting edge surfaces on both sides of the pointed protrusion do not discharge at the same time, the pointed protrusion of the blade is not locally discharged and rounded, and the pointed protrusion is sharply discharged. It can be formed.

Then, after the discharge is formed, the blade surface is rubbed against the abrasive grains, so that the deposits (melted and evaporated substances of the electrodes and the binder) at the time of the discharge fall off the blade surface, and a new cutting edge is formed by the blade. It can be exposed on the surface.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a basic configuration showing one embodiment of a discharge forming method according to the first invention, and FIG. 2 shows a specific example of an apparatus to which the method is applied. . In these figures, a conductive blade 3 is mounted and fixed on a spindle 4 of a grinding device such as a dicing device.
The spindle 4 has an output shaft 4b fitted into an outer peripheral cylindrical portion 4a via an insulating member.
And is rotatably supported by an air bearing or the like. The shape of the cutting edge of the blade 3 is shown as a V-shape in the drawing, but is not necessarily limited to that shape. As shown in FIG. 3, the cutting edge has a pointed protruding portion 9. Various forms of blades 3 can be the subject of discharge formation.

On the other hand, on a chuck table 5 of a grinding device or the like, an electrode 6 having a general shape with respect to the cutting edge shape of the blade 3 is fixed by vacuum suction or the like. The electrode 6 is made of a plate-like material such as iron or tungsten, and has a blade 3 on its surface.
Female wall surfaces 7a and 7b corresponding to the cutting edge surfaces 3a and 3b are formed by engraving grooves 8. An abrasive layer 18 is formed on the groove surface of the electrode 6 as shown in FIG. 6, which will be described later, but the illustration of the abrasive layer 18 is omitted in FIGS. As is clear from FIG. 1, the inclination lengths of the wall surfaces 7a and 7b are set sufficiently longer than the inclination lengths of the cutting edge surfaces 3a and 3b, and the cutting edge surfaces 3a and 3b are separated from the wall surfaces 7a and 7b. It is possible to face each other. When one of the blade surfaces (surface 3a in the figure) and the corresponding wall surface (surface 7a in the diagram) face the discharge state, the other blade surface (3b in the diagram) and the corresponding wall surface (the figure 3a) 7b) is both 7b,
A sufficient insulation distance (insulation interval) that does not cause discharge between 3b is secured. That is, the electrode 6 has its wall surface 7a
7b, a sufficient space is secured, and the blade tip is inserted into the groove 8 of the electrode 6 while retaining a moving space in the X direction. Various cutting edges are used for the blade 3, but in FIG. 1, the cutting edge has a V-shape, so that the wall surface 7 also has a female V-shaped slope. In this regard,
As shown in FIG. 3, when the shape of the cutting edge adopts another shape, the wall surface 7 is formed as a female slope (including a surface) corresponding to the shape.

In FIG. 2, the chuck table 5 is fixed on a work table 19 via an insulating material 22, and the work table 19 is rotatable in the θ direction.
Further, the relative movement of the X, Y, and Z in the three-axis directions with respect to the blade 3 is free. The rotation of θ and the three-axis movement of the X, Y, and Z are controlled by a control device 10 such as a computer. Similarly, the controller 10 controls the amount of advance / retreat of the spindle 4 and the rotational speed of the output shaft 4b. The output shaft 4b is electrically connected to the carbon brush 11, and the output shaft 4b is electrically connected to the blade 3. The carbon brush 11 is connected to a positive terminal of a pulse generator 12, and a negative terminal of the pulse generator 12 is connected to an electrode 6 via a chuck table 5. The pulse generator 12 applies a pulse voltage between the blade 3 and the electrode 6, and the magnitude of the pulse voltage (5 to 10 V in this embodiment), the frequency (5 KHz in this embodiment), and the pulse Duty ratio (25% in this example),
Each discharge condition such as is given by a command from the control device 10.

Further, a current detection sensor (in this embodiment, an ammeter) 13 is provided between the pulse generator 12 and the blade 3, thereby detecting an instantaneous discharge current. Has been sent to The control device 10 performs control such as control of the pulse voltage and, if necessary, adjustment of the interval between the blade 3 and the electrode 6 based on the detected current value. In the figure, reference numeral 14 denotes a nozzle for supplying water and other electric discharge machining liquid between the blade 3 and the electrode 6.

The apparatus according to the first embodiment of the present invention is configured as described above. Hereinafter, a method of forming a discharge at a blade edge using this apparatus will be described.

The device shown in FIG. 2 originally functions as a grinding device for performing dicing or the like. At the time of grinding, a workpiece such as a magnetic head material is suction-fixed to a chuck table 5, and the blade 3 Cutting and grooving are performed. During this grinding process, a pulse generator
No pulse voltage is supplied from 12, and the pulse generator 12 is in an operation stop state.

When the cutting edge of the blade 3 is worn out and deformed during the grinding process, for example, when the V-shaped cutting edge is rounded as shown in FIG.
, The electrode 6 is sucked and fixed instead, and the cutting edge is formed (dressing) as follows.

First, the electrode 6 is correctly fixed to a fixed position of the chuck table 5 using a microscope or the like, and the mounting position of the electrode 6 is set.
X, Y, Z, and θ are input to the control device 10. When the electrode 6 is mounted, the groove 8 of the electrode 6 and the blade 3
The cutting edge is facing as shown in FIG. 2 (more specifically, one side 3a of the blade cutting edge is located immediately above the wall surface 7a of the groove 8).

In this state, the blade 3 is rotated while supplying the electric discharge machining liquid from the nozzle 14, and the blade 3 is moved in the Z direction while relatively reciprocating the electrode 6 in the Y-axis direction so as to approach the electrode 6 side. At the same time, from the pulse generator 12, both 3, 6
When a pulse voltage is applied in between, the cutting edge 3a and the wall surface 7a of the electrode 6
Discharge is started during that time. The discharge current at this time is detected by the current detection sensor 13, and the detection signal is transmitted to the control device 10
Sent to The control device 10 determines a discharge start position in the X and Z directions based on the positions of the two 3 and 6 at which the discharge is started first, and calculates and sets the cut-off amount based on the discharge start position, that is, the setup position. Then, the electrode 6 is moved in the direction of the blade 3 (X
Direction (in this case, if necessary, the blade 3 is sent in the Z direction), the cutting edge surface 3a of the blade 3
Then, the electric discharge proceeds between the electrode 6 and the wall surface 7a of the electrode 6, and the electric discharge causes the rounded portion 15 on one side of the blade edge to be scraped off, so that the one side 3a of the blade edge becomes an inclined surface along the wall surface 7a of the electrode 6. At the time of forming the discharge of the cutting edge surface 3a, the gap between the cutting edge surface 3b and the electrode wall surface 7b is wide, so that no discharge occurs between the two cutting edges 3b and 7b. Since the projection 9 does not come close to the bottom of the groove 8, the projection 9 does not discharge intensively and the projection tip is not consumed locally.

Next, when the blade 3 is moved to the opposite wall surface 7b side (X direction), discharge proceeds similarly between the blade tip surface 3b and the wall surface 7b, and the rounded portion 16 is shaved. It becomes an inclined surface along 7b. Even during this discharge formation, the blade tip surface 3a and the wall surface
Since the discharge does not proceed simultaneously with 7a and the intensive discharge phenomenon of the pointed projection 9 cannot occur, the tip of the pointed projection 9 is never rounded, The tip protruding portion 9 of the blade tip is formed in the original sharp V-shape, and is prepared for the next grinding process.

Generally, in this cutting edge-shaped dressing, the cutting allowance of the rounded portions 15 and 16 is very small as several microns, and therefore, the gap between the discharge blade tip surfaces 3a and 3b and the corresponding wall surfaces 7a and 7b during the progress of discharge. Is not large enough to destabilize the discharge, so there is almost no need to adjust the discharge interval during electric discharge machining.

On the other hand, for example, as shown in FIG. 4, when a V-shaped cutting edge is formed by electric discharge using a disk-shaped blade 17, the cutting allowance becomes large, and therefore, with the progress of electric discharge, Discharge blade tip surfaces 3a, 3b and wall surface 7 facing them
The discharge interval between a and 7b becomes too large, and the discharge state may become unstable. In such a case, the controller calculates the discharge interval between the two based on the detection signal from the current detection sensor, moves the blade 17 or the electrode 6 side in the X direction based on the calculated value, and sets the appropriate interval between the two. Must be maintained at intervals.

As described above, the V-shaped cutting surface 3 having the pointed protrusion 9
In the discharge formation of a and 3b, the discharge formation of the other surface (for example, 3b) is always performed after the discharge formation of one surface (for example, 3a) is completed. Since the discharge is not caused, the pointed protrusion 9 is not locally consumed by the concentrated discharge. Therefore, the pointed protrusion 9 can be formed sharply, which enables high-precision dicing.

In addition, even in the discharge formation of the blade tip surface of another shape shown in FIG. 3, each of the cutting surfaces 3a, 3b, 3c,... Is sequentially formed (the discharge formation of one cutting surface is completed). Each time the next cutting edge surface is discharged, the pointed protruding portion 9 is sharpened so that the respective cutting edge surfaces 3a, 3b, 3c... Can be discharged.

By the way, the electrode 6 on which the discharge is formed is not limited to the plate-like body shown in FIG. 1, but may adopt various forms. For example, as shown in FIG. 5, the electrode 6 may be formed in a roller shape, and the wall surface 7 may be provided on the peripheral surface of the roller by engraving a groove 8.

By forming the groove 8 on the peripheral surface of the roller in this manner, the blade surface 3a, 3b of the blade 3 is opposed to the wall surface 7a or 7b of the groove 8 at a constant interval during discharge formation of the blade. The electrode 6 can be rotated by a motor or the like. Therefore, the entire peripheral surfaces of the wall surfaces 7a and 7b are used as the electrode wall surfaces for electric discharge machining, so that the local wear of the electrode 6 can be avoided, and thereby the shape of the cutting edge can be accurately formed.

In the above embodiment, the electric discharge machining liquid is supplied between the blade 3 and the electrode 6 by the nozzle 14. However, for example, the electric discharge machining liquid is put in a water tank, and the blade tip and the electrode are put in the liquid. 6 may be immersed in the discharge formation.

FIG. 6 shows a detailed form of the groove surface of the electrode 6. The electrode 6 is characterized in that an abrasive layer 18 is formed on the surfaces of the groove wall surfaces 7a and 7b. The abrasive layer 18 is obtained by electrodepositing abrasive grains such as diamond or CBN using, for example, conductive nickel or copper as a base metal.

In this way, if the abrasive layer 18 is formed, after the blade tip is formed by electric discharge using the electrode 6 having the abrasive layer 18, the blade tips 3 a and 3 b are lightly contacted with the abrasive layer 18. If the blade 3 is rotated slowly, the cutting edge surfaces 3a and 3b
And a so-called new cutting edge can be exposed on the cutting edge surface. That is, at the time of electric discharge formation of the cutting edge, the base metal (binder of the abrasive grains) and the electrodes on the cutting edge surface are often melted and evaporated by the discharge heat, and this is undesirably hardened so as to cover the cutting edge. In such a case, after the discharge formation is completed, if the surface of the cutting edge is rubbed against the abrasive layer 18 on the electrode 6 side, the molten solidified material such as the base metal falls off, and a new cutting edge is exposed on the cutting edge surface. You can do it.

In addition, by providing the abrasive layer 18, when forming the blade edge, the blade surface 3a, 3b is lightly contacted with the groove wall surface 7a, 7b of the electrode (specifically, the wall surface of the abrasive layer 18) to form a discharge in a rubbing state. It can be performed. In other words, combined processing of dressing of the cutting edge by rubbing of the abrasive layer 18 and formation of electric discharge between the electrodes is performed, and the forming efficiency of the cutting edge can be greatly improved.

Further, by forming the abrasive layer 18, it is possible to efficiently perform electric discharge formation of the cutting edge surfaces 3a and 3b after grinding (processing such as cutting and grooving) a non-conductive workpiece. The benefit is obtained. That is, after grinding the non-conductive work piece, the non-conductive chips are the blade surface 3a,
3b, which is attached to the cutting edges 3a and 3b and the wall surfaces 7a and 7b.
This causes problems such as destabilizing the discharge conditions (for example, making the discharge voltage non-uniform). In this case, chips can be removed from the edge surfaces 3a, 3b by rubbing the edge surfaces 3a, 3b after grinding the non-conductive workpiece, and after removing the chips, the cutting edge When the discharge is formed, the cutting edge surfaces 3a and 3b can be dressed under stable discharge conditions.

In the embodiment of the present invention, the electrode 6 is formed in a general shape with respect to the cutting edge surfaces 3a and 3b of the blade 3. However, unlike this, the electrode 6 is formed for each cutting edge surface 3a and 3b of the blade 3. The corresponding female electrode wall surface may be formed as a single article, and the electrode may be replaced and used each time each of the blade edge surfaces 3a and 3b is formed by discharge. However, if the electrode 6 is formed in a general shape as in the above embodiment, a plurality of cutting edges can be formed by one electrode, and the work efficiency of electric discharge formation can be improved.

〔The invention's effect〕

As described above, the present invention is configured such that a multi-sided blade tip surface having a pointed protruding portion is formed by discharging sequentially for each cutting edge surface. The sharp protrusion of the cutting edge can be sharply formed by electric discharge, which enables high-precision grinding using the electric discharge formed blade.

In addition, it is possible to remove the discharge deposits attached to the blade tip surface during the discharge formation by the rubbing action with the grindstone, and to expose a new cutting edge on the blade surface.By using this discharge formed blade, the sharpness of the sharpness can be improved. Good and precise grinding can be achieved.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing one embodiment of the present invention, FIG. 2 is a specific device configuration diagram of the embodiment, and FIG. 3 is a diagram showing the relationship between the blade tip shape and the corresponding female electrode wall. FIG. 4 is an explanatory view showing various aspects, FIG. 4 is an explanatory view showing a state of electric discharge machining for forming a V-shaped cutting edge from a plate-shaped blade material, and FIG. 5 is a view showing another embodiment of the electrode in the embodiment. FIG. 6 is a sectional view, FIG. 6 is an explanatory view showing details of a groove forming surface of an electrode, FIG. 7 is an explanatory view showing a proposed example of discharge formation of a blade tip, FIG.
The figure is an explanatory view showing a conventional example of forming a cutting edge. 1 ... spindle, 2 ... dresser, 3 ... blade
3a, 3b ... cutting edge surface, 4 ... spindle, 4a ... outer peripheral cylinder, 4b ... output shaft, 5 ... chuck table, 6 ... electrode, 7, 7a, 7b ... wall surface, 8 ... groove , 9 ... pointed protrusion, 1
0 ... Control device, 11 ... Carbon brush, 12 ... Pulse generator, 13 ... Current detection sensor, 14 ... Nozzle, 15, 16
…… Rounded part, 17 …… Blade, 18 …… Abrasive layer, 19 ……
Work table, 21 ... motor.

Claims (2)

(57) [Claims] 1. An electric discharge forming method for a blade cutting blade having a multifaceted cutting surface having a pointed protruding portion, wherein an electrode having a female wall surface corresponding to each cutting surface of the blade cutting blade is prepared in advance. In advance, one female wall surface is relatively approached to the blade edge surface of the corresponding blade to discharge and form one surface, and after the completion of the discharge formation, the next female wall surface is changed to the blade edge surface of the corresponding blade. To form a discharge on the next blade edge surface, so that the next blade edge surface is discharged in order for each surface, and then each discharge-formed blade edge surface is rubbed against the grindstone surface during discharge formation. A method for forming a discharge on a blade edge, comprising removing the discharge deposits from the blade edge surface. 2. An electrode having a plurality of female wall surfaces corresponding to the respective cutting surfaces of a blade cutting edge and formed in a general shape, wherein one wall surface is in a discharging state with the corresponding cutting surface and the other wall surface is formed. And an insulating distance sufficient to prevent simultaneous discharge between the cutting edge and the corresponding cutting edge surface, and the wall surface of the electrode is formed by electrodepositing an abrasive layer on a conductive metal surface. 2. The method according to claim 1, wherein a discharge is formed on the cutting edge surface and a discharge deposit is removed by the wall surface of the blade.