JPH1158231A - Method and device for truing grinding tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely true various grinding tools such as a ball-shaped grinding tool, a bull nose-shaped grinding tool, a square grinding tool, etc., by one truer. SOLUTION: In a device, a grinding tool 12 to be trued up is so arranged as to face a truer 18 provided with an arched part 18a formed into a recessed shape in the section, and straight parts 18b, 18c continuing to the arched part 18a, the grinding tool 12 is rotated around the rotary shaft and relatively moved in the X, Y or Z-axis direction by an NC feeding means while being pressed to and brought in contact with the front surface of the truer 18. Therefore, the grinding tool 12 is trued up into the desired shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a truing method and apparatus for forming and correcting the shape of a grinding tool such as a resin-bonded grindstone or a metal-bonded grindstone.

[0002]

2. Description of the Related Art In order to mirror-finish a surface including a free-form surface of a mold by performing a displacement cutting method by a grinding tool, ultra-fine diamond abrasive grains formed into a hemispherical shape are bonded to a resin or a metal. A grinding tool having a grindstone joined by materials is used. Since the abrasive grains and the binder (matrix) are gradually removed and deformed with the progress of the grinding process, it is necessary to appropriately truing (forming) the grindstone with accuracy. Conventionally, many devices or methods have been proposed for truing a grindstone.

For example, Japanese Patent Publication No. 59-26962 discloses an apparatus for correcting a grindstone by moving a dresser in two directions perpendicular to each other by a servomotor. This apparatus dresses a grindstone having an arc portion and a linear portion by a rotary dresser provided to be movable in two orthogonal directions. Japanese Patent Application Laid-Open No. Sho 62-130177 discloses a numerically controlled surface grinder provided with a forming dressing device. In this surface grinder, a plurality of single point dressers are arranged on a table, and the grindstone is formed into a desired shape by relatively moving in the X, Y, and Z directions between the grindstone and the table.

Further, Japanese Patent Application Laid-Open No. 2-311266 discloses a method of shaping a grinding wheel by a dressing device attached to a numerically controlled copying grinder. In this method, a disk-shaped rotary grindstone having a semicircular outer peripheral surface is brought into contact with the outer peripheral surface of the disk-shaped metal dresser having a semicircular outer peripheral surface, and the dresser and the grinding wheel are adjusted from the center of the semicircular outer peripheral surface of the dresser. The grindstone is moved along an arc having a radius equal to the sum of the radii of the respective semicircular outer peripheral surfaces to form the grindstone outer peripheral surface.

Japanese Patent Application Laid-Open No. 40274/1984 discloses a numerically controlled turning center provided with a discharge truing / dressing device for a metal bond grinding wheel for grinding. In the discharge truing / dressing apparatus disclosed in this publication, a disk-shaped metal-made rotary truer is brought into contact with a disk-shaped metal bond grinder while rotating, and a predetermined voltage is applied between the two to generate a discharge. This is for performing true-in / dressing of the grindstone.

[0006]

However, the above-mentioned publication does not disclose that a so-called ball-type grinding tool, bull nose-type grinding tool, or square-type grinding tool is trued by one truer. An object of the present invention is to provide a method and an apparatus for accurately truing such various grinding tools with one truer.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to press or approach a grinding tool to be trued on a surface of a truer having a circular arc portion having a concave cross section and a linear portion continuous with the circular arc portion. This is achieved by performing relative movement while facing each other.

That is, the present invention provides a method of truing a grinding tool, wherein a truer having a circular arc portion having a concave cross section and a straight line portion continuous with the circular arc portion is used, and a grinding tool to be trued is opposed to the truer. The gist of the present invention is to provide a method of truing the grinding tool by rotating the grinding tool about its rotation axis and making relative movement by NC feed means along the surface of the truer.

The present invention also relates to a truing apparatus for a grinding tool, wherein a truer having an arc portion having a concave cross section and a straight portion continuous with the arc portion is provided. The gist of the present invention is a truing apparatus for truing the grinding tool, comprising: holding means for rotatably holding the grinding tool; and NC feeding means for relatively moving the grinding tool along the surface of the truer while rotating the grinding tool.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. A truing apparatus 10 (hereinafter, referred to as an apparatus 10) for a grinding tool according to an embodiment of the present invention includes:
A truer 18 is fixed to the upper surface of the base 11. The truer 18 has an arc portion 18a formed in a concave arc shape having a predetermined radius in a cross section, and a vertical portion 18 continuous with the arc portion 18a and formed in a straight line in a cross section.
b and a horizontal portion 18c. The grinding tool 12 to be trued is arranged opposite the truer 18. FIG.
In the embodiment shown in FIG. 1, the grinding tool 12 is illustrated as a hemispherically formed ball-shaped grinding tool having a radius smaller than the radius of curvature of the arc portion 18a of the truer 18.

The grinding tool 12 includes a vertical portion 18 of a truer 18.
The spindle device 14 is rotatably mounted on a tip end of a spindle 14a of a spindle device 14 around a rotation axis O1 parallel to b. The spindle device 14 is perpendicular to the direction of the rotation axis O1 (hereinafter referred to as the Z-axis direction) and the rotation axis, and is orthogonal to each other.
It is configured to be movable in the directions (hereinafter referred to as X-axis direction and Y-axis direction), and the NC controller (not shown) accurately positions the tip of the grinding tool 12 with respect to the truer 18. Relative motion in any direction can be performed. In the embodiment shown in FIG. 1, the grinding tool 12 includes a fine-grain resin-bonded grindstone, and can be formed by, for example, bonding alumina abrasive grains having an average particle diameter of 4 to 5 μm with a melamine resin. Also Tsurua 1
8 can be formed of a sintered body of diamond or CBN (cubic boron nitride).

As shown in FIG. 2, the grinding tool 12 includes a ball-shaped grinding tool 12 (FIG. 2A) having a grindstone having a combination of a hemispherical tip and a cylindrical base end, and a cylindrical grinding tool. A bullnose-shaped grinding tool 12 ′ having a grinding wheel whose outer peripheral portion is formed into a quadrant in cross section (FIG. 2B);
Square grinding tool 12 "having a cylindrical grinding wheel (FIG. 2)
(C)) Alternatively, the shape may be a combination of these shapes. In short, the shape of the grinding tool 12 may be a curved portion having a radius equal to or smaller than the radius of curvature of the concave arc portion 18 a of the truer 18, a cylindrical surface portion to be trued by the vertical portion 18 b of the truer 18, or a horizontal portion 1 of the truer 18.
Any shape may be used as long as the shape includes an end face portion trued by 8c. The square grinding tool 12 ″ does not have a clear curved surface portion that is to be swallowed by the arc portion 18a of the truer 18 unlike the ball grinding tool 12 and the bull nose grinding tool 12 ′. 1
It can be considered that the radius of curvature of the curved surface portion 2 'is extremely small.

Hereinafter, the operation of the first embodiment will be described by taking as an example the case where the ball-shaped grinding tool 12 is trued. First, the grinding tool 12 to be trued is mounted on the tip end of the spindle 14a of the spindle device 14 driven by the NC feeding means. Next, the virtual semicircle of the ball portion to be formed at the tip of the grinding tool 12 and the surface of the concave arc portion 18a of the truer 18 are pressed so as to come into contact with each other while having a common tangent line. , The grinding tool 12 and the spindle device 14
While rotating about the rotation axis O1 as a center,
Move in the axis, Y-axis, and Z-axis directions. Thus, a semicircular ball portion having a radius equal to or smaller than the radius of curvature of the arc portion 18a of the truer 18 is formed at the tip of the grinding tool 12. Further, in order to grind the side surface of the cylindrical portion of the grinding tool 12,
While rotating the grinding tool 12, the vertical portion 1 of the truer 18
What is necessary is just to press the side surface of the grinding tool 12 to 8b.

Further, the bull nose type grinding tool 12 'shown in FIG. 2B has a flat end surface in addition to a cylindrical side surface and a quadrant-shaped curved portion in cross section. The side surface and the curved portion of the bull nose type grinding tool 12 'can be formed in the same manner as the ball type grinding tool 12 described above. That is, the side surface can be trued by the vertical portion 18b of the truer 18, and the curved portion can be trued by the concave curved portion 18a of the truer 18. The end face of the bull nose type grinding tool 12 ′ can be trued by pressing against the horizontal portion 18 c of the truer 18. In the case of the square grinding tool 12 "shown in FIG. 2C, the side surface of the grinding tool 12" is pressed against the vertical portion 18b of the truer 18, and the end surface is pressed against the horizontal portion 18c.

Next, a second embodiment of the present invention will be described with reference to FIG. This shows the case of discharge truing as opposed to the mechanical truing of the first embodiment. 3, the same components as those in the embodiment of FIG. 1 are designated by the same reference numerals. The truing device 10 according to the present embodiment includes a concave processing tank 16.
And a rotationally symmetric rotating tool 18 ′ fixed in the processing tank 16. The rotary truer 18 'is similar to the truer 18 of the first embodiment except that it has a rotationally symmetrical shape, and has a concave arc portion, a vertical portion as a straight portion continuous with the arc portion, and a horizontal portion. Have. The material is
It is made of copper, graphite or the like. In the processing tank 16,
Similarly to a general electric discharge machine, an electric discharge machining fluid is supplied from a machining fluid supply source via a supply pipe 22 and the rotary tool 1
8 'is immersed in the electric discharge machining fluid. The processing tank 16 is provided with a rotating shaft 20 a of a drive motor 20 fixed to the upper surface of the base 11.
, And is driven to rotate about a vertical rotation axis O.

A grinding tool 12 to be trued is provided in a processing tank 16 and opposed to a rotating truer 18 '.
As in the first embodiment, the grinding tool 12 is mounted on the tip of the spindle 14a of the spindle device 14 driven by NC.
The tip portion can be precisely positioned in the X-axis, Y-axis, and Z-axis directions by the NC device, or relatively moved along an arbitrary shape. However, in this embodiment, the grinding tool 12
A metal bond grindstone is formed by bonding and forming diamond abrasive grains with a metal binder. As a grinding tool to be trued, in this embodiment, a ball-shaped grinding tool 12 is shown as in the embodiment of FIG. 1, but a bull nose-shaped grinding tool 12 '(FIG. 2B) and a square-shaped grinding tool 1 are used.
2 "(FIG. 2 (C)).

The main shaft 14a of the main shaft device 14 is connected to a power supply 24 via a power supply brush 26. In order to electrically disconnect the spindle device 14 from the power supply 24, the spindle device 14 is provided with an insulator 14b. The rotary ruler 18 'is also electrically connected to the power supply 24 via a power supply brush (not shown). In this manner, the power supply 24 applies a desired voltage between the grinding tool 12 to be trued and the rotating truer 18 '.

Next, the operation of the second embodiment will be described.
The electric discharge machining liquid is supplied to the machining tank 16 through the supply pipe 22, and when the electric discharge machining liquid is filled in the machining tank 16, the rotating tool 18 ′ is immersed in the electric discharge machining liquid. Grinding tool 12
When the grinding tool 12 approaches and faces the surface of the rotating ruler 18 'while applying a voltage between the rotating tool 18' and the rotating tool 18 ', a discharge phenomenon occurs between the two. While maintaining this state, the tip of the grinding tool 12 is rotated by the rotation of the grinding tool 12 and the rotary truer 18 ′ as described in the first embodiment.
By moving in the X-axis, Y-axis, and Z-axis directions by the C feed means, a discharge phenomenon occurs, a metal part as a binder is removed, and the grinding tool 12 is trued into a desired shape.

In the second embodiment, the rotating truer 1
Although 8 'was immersed in the electric discharge machining fluid, the electric discharge machining fluid may be sprayed on the machining area, that is, the contact portion between the rotary tool 18' and the grinding tool 12. Next, a third embodiment of the present invention will be described with reference to FIG. Referring to FIG. 4, a truing apparatus 10 for a grinding tool according to the present embodiment includes a hollow cylindrical frame 30 provided on an upper surface of a base 11, and a processing tank 32 for storing a grinding fluid in the frame 30. Is attached. In the processing tank 32, an anode fixing member 34 is supported by the frame 30 so as to be rotatable about a rotation axis O. The anode fixing member 34 is formed of an electrically insulating material such as acrylic into a substantially cylindrical shape having a concave portion 34a.
4b. Flange part 34 of anode fixing member 34
A seal member 30 a such as an O-ring is provided between the b and the frame 30 to prevent the grinding fluid from entering the inside of the frame 30.

In the present embodiment, the grinding fluid is composed of a suspension in which carboxymethyl cellulose (CMC) and alumina oxide abrasive grains are dispersed in ion-exchanged water. A grinding fluid having a relatively high viscosity was used in order to prevent the grinding fluid from scattering due to centrifugal force and to disperse relatively large alumina abrasive grains as free abrasive grains in the grinding fluid. More specifically, about 5% by weight of alumina abrasive grains were dispersed in the CMC aqueous solution, and the viscosity was maintained at 45 to 50 cP.
The particle size of the alumina abrasive was 1.5 to 6.7 μm. A grinding fluid circulation device 38 is provided to circulate the grinding fluid in the processing tank 32. The grinding fluid circulation device 38 is a pump 3
8a, the pump 38a sucks the grinding fluid from the bottom of the processing tank 32 through a pipe 38b,
8c, the upper part of the processing tank 32, specifically, the processing tank 3
The grinding fluid is circulated over the concave portion 34a of the anode fixing member 34 in 2. Pump 38a can preferably be a tubing pump.

In the concave portion 34a of the anode fixing member 34, a truer 18 "as a positive electrode is fixed concentrically to the anode fixing member 34 along the rotation axis O.
8 ″ is an arc-shaped portion 18 ″ a having a concave cross section made of a corrosion-resistant metal material such as stainless steel, and the arc-shaped portion 1 ″.
8 "a, two straight portions 18" b, 1
It is formed in the shape of a rotating body having 8 ″ c (see FIG. 5).
A drive motor 36 for rotating and driving the anode fixing member 34 about the rotation axis O is fixed on the upper surface of the base 11 inside the frame 30.
4 is attached to the rotating shaft 36a of the drive motor 36. The drive motor 36 can be rotated at, for example, 1500 rpm. Thus, the truer 18 ″ is driven to rotate about the rotation axis O together with the anode fixing member 34 by the drive motor 36.

In the concave portion 34a of the anode fixing member 34, a negative electrode 40 is further provided with a small gap δ from the truer 18 ″. The negative electrode 40 is made of, for example, graphite, ″.
The small gap δ is fixed to a fixing portion (not shown) of the device 10 so as to be adjustable. A desired DC voltage is applied between the truer 18 ″ and the negative electrode 40 by the power supply device 42.

In the recess 34a of the anode fixing member 34, a grinding tool 12 is further provided as a grinding tool to be trued. The grinding tool 12 is mounted on the tip of a spindle device 14 that rotates about a rotation axis O ₁ parallel to the rotation axis O of the truer 18 ″. The spindle device 14 is mounted in the Z-axis direction along the rotation axis O ₁ and It is configured to be movable in two directions perpendicular to the rotation axis, that is, in the X and Y axis directions, so that the tip of the grinding tool 12 can be accurately positioned with respect to the truer 18 ″. For example, grinding tool 1
Reference numeral 2 includes an ultrafine resin-bonded grindstone, and is formed by bonding diamond abrasive grains having an average particle size of 4 to 5 μm with a melamine resin. As shown in FIG. 2, the grinding tool 12 includes a ball-shaped grinding tool 12, a bull nose-shaped grinding tool 1,
2 ', a square grinding tool 12 "or a combination of these shapes. In short, the shape of the grinding tool 12 is a concave arc 18" of a truer 18 ".
a curved surface portion having a radius equal to or less than the radius of curvature of a
Any shape having a cylindrical surface portion that can be trued by the 8 ″ straight portion 18 ″ b and an end surface portion that is trued by the straight portion 18 ″ c of the truer may be used.

Hereinafter, the operation of the embodiment of the present invention will be described.
Generally, when alumina abrasive grains are dispersed in an aqueous solution in which CMC is dissolved, the hydrophilic groups of CMC release metal ions and become negatively charged, and the abrasive grains are adsorbed to the hydrophobic groups. A grinding fluid consisting of a suspension in which abrasive grains are dispersed in a CMC solution,
When a voltage is applied between the 8 ″ and the negative electrode 40 to form an electric field in a minute gap between them, the abrasive grains that are hydrophobically adsorbed on the CMC are attracted to the surface of the truer 18 ″ by the electrophoresis phenomenon. Then, the CMC and the abrasive grains sucked on the surface of the truer 18 ″ are hydrophobically adsorbed on the surface of the truer 18 ″, and a gel-like film 44 having a high abrasive grain concentration is formed as shown by a dashed line in FIG. .

In this state, the truing of the grinding tool 12 is performed by pressing the truer 18 ″ and the grinding tool 12 against each other while rotating them relative to each other. More specifically, the average grain size of the diamond abrasive grains of the grinding tool 12 is performed. By using free abrasive grains having an average particle size equal to or greater than that of the abrasive tool, diamond abrasive grains of the grinding tool 12 and melamine resin as a binder are removed, and the grinding tool 12 is mainly used.
Truing is performed. Conversely, by using free abrasive grains having an average grain size equal to or less than the average grain size of the diamond abrasive grains of the grinding tool 12, only the melamine resin of the grinding tool 12 is removed, and Twelve dressings are performed.

The truing is mainly performed by strongly pressing the grinding tool 12 against the surface of the truer 18 "while relatively rotating the grinding tool 12 and the truer 18". Dressing is mainly performed by bringing the grinding tool 12 into contact with the gel-like film 44 formed on the surface of the truer 18 ″. That is, by pressing the grinding tool 12 so as to contact the surface of the truer 18 ″, Both the diamond abrasive grains of the grinding tool 12 and the melamine resin as a binder are removed, and the grinding tool 12
By positioning the grinding tool 12 so that the shape of the contact surface with the 8 ″ is transferred and the grinding tool 12 is in contact with the gel-like film 44 formed on the surface of the truer 18 ″ instead of the truer 18 ″, The gel-like film acts as a polisher, and only the melamine resin of the grinding tool 12 is removed, and the grinding tool 12 is dressed.

The above two methods, namely, appropriately selecting the particle size of the loose abrasive grains, and the method of selecting the truer 18 ″ of the grinding tool 12
By properly selecting the pressing method, the truing and dressing of the grinding tool 12 can be optimized. In other words, by efficiently pressing the grinding tool 12 against the surface of the truer 18 ″ by using loose abrasive grains having an average grain diameter equal to or larger than the average grain diameter of the diamond abrasive grains of the grinding tool 12, the efficiency is improved. Truing can be performed, and the grinding tool 12 is formed on the surface of the truer 18 ″ by using free abrasive grains having an average grain diameter equal to or less than the average grain diameter of the diamond abrasive grains of the grinding tool 12. The dressing can be efficiently performed by contacting the film 44. The feed operation of the X, Y and Z axes of the NC feed means is controlled in accordance with each of the grinding tool shapes as shown in FIGS. 2 (a), 2 (b) and 2 (c) so that the grinding tool has a desired shape. Can be truing. In the first, second and third embodiments, the spindle device 14 is replaced by a spindle device of an NC machine tool, and the base 11 is
C Fix to one corner on the table of the machine tool
If the need for truing arises while machining the workpiece in 2,
The truing device 10 immediately installed in one corner of the table
May be configured to perform truing and then continue the grinding of the workpiece with the tool.

[0028]

According to the present invention, grinding tools of various shapes can be efficiently and accurately formed by a single truer with a simple configuration using a simple-shaped truer comprising a concave circular arc portion and a straight line portion following the circular arc portion. You can truing.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a truing device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a grinding tool, wherein (a) is a ball-shaped grinding tool, (b) is a bull nose-shaped grinding tool, and (c) is a square-shaped grinding tool.

FIG. 3 is a schematic sectional view of a truing device according to a second embodiment of the present invention.

FIG. 4 is a schematic sectional view of a truing device according to a third embodiment of the present invention.

5 is a partially enlarged view of the truer shown in FIG. 4, showing a film formed on the surface of the truer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Truing device 11 ... Base 12, 12 ', 12 "... Grinding tool 14 ... Spindle device 16, 34 ... Processing tank 18, 18', 18" ... Truer 20, 36 ... Drive motor 24, 42 ... Power supply device 40 … Negative electrode

Claims (5)

[Claims] 1. A truing method for a grinding tool, comprising: using a truer having a circular arc portion having a concave cross-section and a straight line portion continuing to the circular arc portion, wherein a grinding tool to be trued is opposed to the truer, and disposed. A method of truing the grinding tool by rotating the grinding tool about its rotation axis and making relative movement by NC feed means along the surface of the truer. 2. A truing apparatus for a grinding tool, comprising: a truer having an arc portion having a concave cross section and a straight portion continuous with the arc portion; and a grinding tool to be trued rotatable about its rotation axis. A truing apparatus for truing the grinding tool, comprising: holding means for holding; and NC feeding means for causing the grinding tool to rotate and relatively move along the surface of the truer. 3. A truing apparatus for a grinding tool, comprising: a truer made of diamond, CBN, or the like, having an arc portion having a concave cross section and a straight portion continuous with the arc portion; A truing apparatus for truing the grinding tool, comprising: holding means for rotatably holding the grinding tool; and NC feeding means for relatively moving the grinding tool while pressing against the surface of the truer while rotating the grinding tool. 4. A truing apparatus for a grinding tool, comprising: a truer having an arc portion having a concave cross section and a straight portion continuing to the arc portion; and a grinding tool to be trued held rotatably about its rotation axis. A power supply device for applying a predetermined voltage between the grinding tool and the truer to generate a discharge phenomenon; and a rotating and rotating the grinding tool so as to approach and face the truer, along a surface of the truer. NC feeding means for causing relative movement of the grinding tool, and a truing device for truing the grinding tool. 5. A truing apparatus for a grinding tool, comprising: a truer having an arc portion having a concave cross section and a straight portion continuous with the arc portion; and a grinding tool to be trued rotatably about a rotation axis thereof. Holding means, an electrophoresis apparatus for immersing the truer and the grinding tool in a grinding fluid in which free abrasive grains are dispersed, and attracting the free abrasive grains to the surface of the truer by an electrophoretic phenomenon, and rotating the grinding tool. NC feeding means for performing relative movement along the surface of the truer while performing the truing, and a truing apparatus for truing the grinding tool.