JPH10202536A - Resinoid bonded grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resinoid bonded grinding wheel having higher heat resistance than a conventional resinoid bonded grinding wheel in the resinoid bonded grinding wheel bonded by an epoxy resin. SOLUTION: In a resinoid bonded grinding wheel 10, a resin bonding agent is constituted of an epoxy resin bonding agent 22 in which a glass transition point (Tg) is 130( deg.C) or more. Therefore, bonding force of the epoxy resin bonding agent 22 is maintained sufficiently high even if the temperatures of grinding liquid and a working point rise during working because the epoxy resin bonding agent in which Tg is sufficiently high is used as bonding agent. Namely, the temperature is maintained to a range which is sufficiently lower than a temperature in which heat resistance of the epoxy resin bonding agent 22 becomes a problem. Therefore, grinding working can be easily performed even if a temperature adjustment of grinding liquid in particular is not performed because heat resistance of the resinoid bonded grinding wheel 10 bonded with epoxy resin bonding agent 22 is improved sufficiently higher than a conventional resinoid bonded grinding wheel and lowering of working performance (working number) according to a rise of a temperature is not substantially generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resinoid grinding wheel.

[0002]

2. Description of the Related Art For example, for high-speed rough grinding or free grinding,
Generally, resinoid grinding wheels with a lower elastic modulus and higher strength than vitrified grindstones are used. Therefore, a resinoid grinding wheel using an epoxy resin having a lower elastic modulus than a phenol resin as a binder is often used. Resinoid grinding wheels in which abrasive grains are bonded with such an epoxy resin are generally manufactured by dispersing and curing the abrasive grains in a liquid epoxy resin, so that the resin retains the abrasive grains (wettability). )
And the abrasive grains are less likely to fall off.

[0003]

However, the resinoid grinding wheel using the above-described epoxy resin has a lower heat-resistant temperature than the resinoid grinding wheel using a phenol resin, and increases the temperature of the grinding fluid and the grinding point. There is a problem that the processing accuracy is likely to be reduced due to the above. That is, for example, when the environmental temperature is high in summer or the like, or when the grinding resistance is greatly increased due to a dimensional change caused by thermal expansion or the like during processing of the workpiece, the temperature of the grinding fluid or the grinding point is increased. For example, the temperature of the grinding fluid can be raised to a high temperature of about 60 (° C) or more. As a result, the grinding performance is reduced in a short time, and the desired processing accuracy cannot be obtained. In addition, when the environmental temperature is low in winter or when the grinding is performed in a temperature-controlled room, or when a temperature control device for a grinding fluid is used, a resinoid grinding wheel using epoxy resin is used. High processing accuracy is obtained because the grinding fluid and the grinding point are not heated to a temperature at which the heat resistance becomes a problem, but this greatly limits the use conditions of resinoid grinding wheels using epoxy resin as a binder, The scope of application has been narrowed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resinoid grinding wheel having a higher heat resistance than a conventional resinoid grinding wheel bonded with an epoxy resin. is there.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is a resinoid grinding wheel containing abrasive grains and a resin binder for bonding the abrasive grains to each other. (A) the resin binder has a glass transition point
130 (° C) or more of epoxy resin.

[0006]

As described above, in the resinoid grinding wheel, the resin binder is made of an epoxy resin having a glass transition point of 130 (° C.) or more. Therefore, since the epoxy resin having a sufficiently high glass transition point is used as a binder, the bonding force of the epoxy resin is maintained sufficiently high even if the temperature of the grinding fluid or the grinding point increases during processing. .
Therefore, the heat resistance of the resinoid grinding wheel bonded with the epoxy resin is sufficiently improved as compared with the conventional case, and the grinding process can be easily performed without particularly adjusting the temperature of the grinding fluid.

[0007] Incidentally, the problem of the decrease in grinding performance described above is as follows.
It largely depends on the thermal properties of the resin binder that binds the abrasive grains. That is, in general, the binding force of the resin binder is reduced with an increase in temperature, but the size and shape of the resinoid grinding wheel are changed, and as a result of this binding force being reduced, the holding power of the abrasive grains by the resin binder is reduced. This is considered to be due to the fact that the resin binder becomes insufficient and the resin binder easily falls off, and the resin binder itself is largely scraped off from the surface by friction with the work material. In conventional resinoid grinding wheels using epoxy resin, the type of resin binder is determined exclusively based on the elastic modulus, strength, etc.As a result, the epoxy resin binder generally has a glass transition point of about 100 (° C) or less, for example. Was used. Therefore, since the temperature of the grinding fluid and the grinding point can be raised to a temperature near the glass transition point where the bonding force of the epoxy resin binder is greatly reduced by softening,
The reduction in grinding performance based on the change in the size and shape of the grinding stone occurred.

[0008]

In another preferred embodiment of the present invention, the main component of the epoxy resin is bisphenol A type, bisphenol F
Glycidyl ether type, alicyclic type, glycidyl ester type, glycidylamine type, or long-chain aliphatic type, such as type, halogenated bisphenol type, and novolak type, and curing agent is aliphatic polyamine, polyamideamine. , Spirocyclic amines, aromatic polyamines, alicyclic polyamines, long-chain aliphatic polyamines, or acid anhydrides. More preferably, the base is of the novolak, alicyclic, glycidylamine, or long chain aliphatic type. When these are used as the main components, higher heat resistance can be obtained. In particular, among the above, the alicyclic type has a low viscosity, and thus is suitably used when a grindstone is manufactured by casting. The epoxy resin obtained by these combinations has a glass transition point of, for example, a maximum of about 240 (° C), but is 130 (° C) or more, preferably 140 (° C) or more.
If so, an epoxy resin having a glass transition point at any temperature can be applied to the present invention.

[0009] Preferably, the epoxy resin has an elastic modulus of 5 (GPa) or less. In this case, since the elastic modulus is sufficiently low, a grinding wheel more suitable for grinding with a large grinding allowance can be obtained.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following examples, the dimensional ratios and the like of each part are not necessarily drawn accurately.

FIG. 1 is a diagram showing a cross section of a resinoid grinding wheel 10 according to one embodiment of the present invention. In the figure, a resinoid grinding wheel 10 has, for example, an outer diameter of 585 (mm) × a thickness of 75 (m).
m) is a disk-type grinding wheel for double-sided surface grinding integrally formed with dimensions of about the same, and as shown vertically separated by a dashed line, a use portion 14 having a use surface 12,
And a mounting portion 18 having a mounting surface 16. The resinoid grinding wheel 10 has a particle size of, for example,
Alumina (Al ₂ O ₃ ) based abrasive grains 20 are bonded by an epoxy resin binder 22. The mounting portion 18 has a radial direction for mounting on a flange of a double-sided surface grinder. A plurality of nuts 24, which are arranged evenly in the circumferential direction on several circumferences, are embedded in the mounting surface 16 with the end faces exposed. The used portion 14 is composed of, for example, 50 volume parts of the abrasive grains 20, 20 volume parts of the epoxy resin binder 22, and 30 volume parts of the pores. The epoxy resin binder 22 has a glass transition point Tg of 140 to 205 measured by, for example, DSC (differential scanning calorimetry defined by JIS K 7121-1987).
(° C.) and an elastic modulus of about 5 (MPa). The measured value by the DSC method is based on the TMA method (JIS K
The value is almost the same as the value measured by the linear expansion coefficient test method specified in 7197-1991.

The above-mentioned resinoid grinding wheel 10 is manufactured, for example, as follows. That is, first, for example, about 70 parts by volume of the abrasive grains 20 and about 30 parts by volume of the liquid epoxy resin 22 are weighed and mixed by a mixer. Thereafter, the mixed and stirred liquid material is poured into a mold having a predetermined size, and heat-treated at a temperature of, for example, about 160 (° C.) for about 4 hours to cure the epoxy resin until its hardness is sufficiently increased. Thus, the resinoid grinding wheel 10 shown in FIG. 1 is obtained.

FIG. 2 is a diagram showing a use state of the above-mentioned resinoid grinding wheel 10 in a double-sided surface grinding machine. In the figure, the double-sided surface grinder is provided with a pair of flanges 28, 28 provided opposite to each other and driven to rotate by rotating shafts 26, 26, respectively. A plurality of bolts 30 are attached to the facing surfaces of 28, 28. A guide 34 is provided between the pair of resinoid grinding wheels 10 and 10 for continuously feeding a work material 32 such as an outer ring of a bearing race, for example, in one direction from the back surface to the front surface of the paper. Resinoid grinding wheels 10, 10
Are located apart from each other by a distance corresponding to the processing dimensions of the work material. In this double-sided surface grinder, the work material 32 is supplied between the pair of resinoid grinding wheels 10, 10 while the pair of resinoid grinding wheels 10, 10 is rotated in the directions indicated by arrows in the drawing. Thereby, the plurality of workpieces 32 are sequentially processed into a predetermined size.

In the double-sided surface grinding machine shown in FIG. 2, the width (length in the axial direction) of the outer race of the bearing race is generated by the resinoid grinding wheel 10 using various compositions of epoxy resin as a binder. The material grinding result is
Table 1 below and FIG. 3 show a comparison with the results of grinding with a conventional resinoid grinding wheel using an epoxy resin having a low g.
Shown in Table 1 also shows the compositions of the epoxy resins of the present example and the comparative example, and FIG. 3 shows the relationship between the grinding fluid temperature and the number of processes for each glass transition point Tg. In Table 1, "Bis A type" in the column of "Main agent" means "Bisphenol A type", and "Tg" is a cured product of an epoxy resin binder alone containing no abrasive grains,
It is a value measured by the C method. The “number of processing” is the number of pieces that can be processed per wheel set at each temperature of the grinding fluid when the temperature of the grinding fluid is maintained at the respective temperature shown in the item column. Indicates that processing was not possible. In this "number of processing" column, "reduction rate" is 15
The percentage of the decrease in the number of processes (N80) at 80 (° C.) relative to the number of processes (N15) at (° C.) ([N15−N80｝ / N15]) is expressed as a percentage. The processing conditions are as follows. [Processing conditions] ・ Wheel peripheral speed: 1800 (m / min) ・ Work material: SUJ-2 (HRB hardness 90-100) ・ Work material allowance: 1 (mm)

[0015]

[Table 1]

As is clear from Table 1 and FIG.
According to the resinoid grinding wheel 10 of the present embodiment, the number of machining hardly decreases even when the temperature of the grinding fluid is as high as 60 (° C.) or more, and is reduced from a low (15 ° C.) to a high (80 ° C.). ) High grinding performance is maintained. Under general processing conditions, the temperature of the grinding fluid can rise to about 70 (° C.), but in the present embodiment, as described above, a higher temperature of 80 (° C.)
The practical processing temperature range (temperature range of the grinding fluid) is 10 to 70, since the number of machining hardly decreases to a temperature of about
It can be said that the grinding performance is maintained in a sufficiently high range in the temperature range of about (° C). In particular, in Example 8 in which the alicyclic epoxy resin was used as the main agent, the structure of the resinoid grinding wheel 10 was formed more evenly because it had a preferable viscosity when the liquid material was poured into the mold in the above-described manufacturing process. As can be seen from the above table, a higher grinding capacity is obtained.

On the other hand, in the comparative example, the resinoid grinding wheel using an epoxy resin having a low Tg is 40 to 60.
(° C), the number that can be processed sharply decreases, and the grinding performance is greatly reduced. Therefore, although sufficient grinding performance can be obtained in winter or when the temperature of the grinding fluid is controlled within a certain range, there is a problem that the grinding performance tends to decrease in an environment where the temperature of the grinding fluid tends to increase, such as in summer. there were.
In the comparative example, a large decrease in the number of processes (that is, a large decrease in grinding performance) is observed from a temperature lower than Tg. This is because the temperature at the grinding point of the work material 32 is lower than the temperature of the grinding fluid. It is considered that the decrease in the bonding strength of the epoxy resin due to the temperature rise is accelerated by the alkali components and additives contained in the grinding fluid. Even when the temperature of the epoxy resin is lower than Tg, when the temperature becomes close to that, the strength decreases in accordance with the temperature rise, and such a phenomenon occurs. By the way, in the resinoid grinding wheel of the example, since the Tg of the epoxy resin binder is sufficiently higher than the grinding fluid temperature in the above temperature range, the temperature does not reach the temperature at which the strength decreases, so that No acceleration of strength reduction can occur.

FIG. 4 shows the relationship between the Tg and the reduction rate of the number of processes in Table 1 above, with the horizontal axis representing Tg and the vertical axis representing the reduction rate. As is apparent from the figure, Tg is 120
In the range below (° C), a large reduction rate of about 90 (%) or more is exhibited, but in the range of Tg of 130 (° C) or more, the reduction rate is rapidly reduced, and the grinding fluid is heated to about 80 (° C). In this case, the reduction in the number of processings in the case of about 15 (° C.) is suppressed. In particular, Tg is about 140 (° C.) or more, preferably 145
(° C.) In the above range, even if the temperature of the grinding fluid becomes high, the number of processing is maintained at the same number as that of the case of low temperature, and the reduction in grinding performance is substantially eliminated. In the figure, Tg is 80
In the case of (° C) or less, the reduction rate is indicated as 100 (%) because machining was impossible at a grinding fluid temperature of 80 (° C). When the Tg was 190 (° C) or more, the number of processing at 80 (° C) became larger than the number of processing at 15 (° C), and the reduction rate became negative. However, this was merely a measurement variation. Therefore, it is considered that the number of processes does not substantially decrease, so it is displayed at the position of 0 (%).

In short, in this embodiment, in the resinoid grinding wheel 10, the resin binder has a Tg of 130.
(° C.) It is composed of the epoxy resin binder 22 described above.
For this reason, since the epoxy resin binder 22 having a sufficiently high Tg is used as the binder, even if the temperature of the grinding fluid or the grinding point increases during processing, the epoxy resin binder 22 may be used.
Is maintained sufficiently high. That is, the temperature is maintained in a range sufficiently lower than the temperature at which the heat resistance of the epoxy resin binder 22 becomes a problem. Therefore, the heat resistance of the resinoid grinding wheel 10 bonded with the epoxy resin binder 22 is sufficiently increased as compared with the conventional case, and the processing performance (the number of processing) accompanying the temperature rise does not substantially decrease.
In particular, the grinding can be easily performed without adjusting the temperature of the grinding fluid.

In this embodiment, the epoxy resin binder 22 has an elastic modulus of about 5 (GPa). for that reason,
Since the elastic modulus is sufficiently low, more excellent grinding performance can be obtained in a raw material grinding process of a width dimension such as a bearing race outer ring having a large grinding allowance as shown in FIG.

While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be embodied in still another embodiment.

For example, in the embodiment, the case where the present invention is applied to the disk-type resinoid grinding wheel 10 for a double-sided surface grinder has been described. However, the present invention is applied to a resinoid grinding wheel used in an environment where a temperature rise is expected. If so, the present invention is similarly applied to various grinding wheels such as a ring-type surface grinding wheel, a cup-type grinding wheel, a cylindrical grinding wheel, a centerless grinding wheel, and an inner surface grinding wheel.

In the embodiment, the resinoid grinding wheel 10 using the abrasive grains 20 made of alumina having a grain size of about # 60 has been described. However, silicon carbide (SiC) abrasive grains,
The present invention is similarly applied to a resinoid grinding wheel using other general abrasive grains such as zirconia (ZrO ₂ ) abrasive grains, and the grain size of the abrasive grains is appropriately changed.

Further, in the embodiment, the entire resinoid grinding wheel 10 is constituted by abrasive grains bonded by an epoxy resin binder 22. However, a segment wheel is provided around a core made of resin, stainless steel or the like. The present invention is similarly applied to an attached segment type grinding wheel.

In the embodiment, the Tg is 205 (° C.)
Hereinafter, an epoxy resin binder 22 having an elastic modulus of about 5 (MPa) has been used as a binder, but about 130 to 240 (° C.)
Various commonly known epoxy resins having a Tg of preferably about 140 to 240 (° C.) may be used.
And the elastic modulus can be appropriately changed.

In the embodiment, the curing temperature after the liquid is poured into the mold in the manufacturing process of the resinoid grinding wheel 10 is appropriately changed according to the type of the epoxy resin binder 22.

In the embodiment, the resinoid grinding wheel 10 is composed of 50 parts by weight of the abrasive particles 20, 20 parts by weight of the epoxy resin binder 22, and 30 parts by weight of the pores. Is appropriately changed depending on the grinding application. For example, the present invention can be applied to a nonporous resinoid grinding wheel.

Although not specifically exemplified, the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a view showing a cross-sectional structure of a resinoid grinding wheel according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating a use state of the resinoid grinding wheel of FIG. 1;

FIG. 3 is a diagram showing a relationship between a grinding fluid temperature and the number of processes for each glass transition point.

FIG. 4 is a diagram showing the relationship between the glass transition point and the number of reductions in the number of processes.

[Explanation of symbols]

 10: Resinoid grinding wheel 20: Abrasive particles 22: Epoxy resin binder

Claims (1)

[Claims] 1. A resin grinding wheel containing abrasive grains and a resin binder for bonding the abrasive grains to each other, wherein the resin binder is made of an epoxy resin having a glass transition point of 130 (° C.) or more. A resinoid grinding wheel characterized by being formed.