JP4523707B2 - Honing wheel for gears - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gear honing grindstone for polishing a tooth surface of a gear.
[0002]
[Prior art]
For example, gears used in automobile transmissions and the like are subjected to a honing process after quenching in order to reduce gear noise to remove quenching distortion and improve tooth surface accuracy. For such processing, for example, an internal tooth grindstone in which general abrasive grains such as alumina oxide and silicon carbide are bonded with a thermosetting resin such as phenol and epoxy to form a highly accurate inner peripheral tooth on the inner peripheral surface is used. It has been. For example, a gear honing grindstone having a plurality of inner peripheral teeth that mesh with outer peripheral teeth of a gear (workpiece). Such an internal grinding wheel for honing is dressed with a dress gear in which diamond abrasive grains are fixed to the surface by electrodeposition or the like prior to the honing process, and then the internal teeth are meshed with the gear-like workpiece, As the workpiece is reciprocated in the axial direction and rotated around the axial center, the tooth surface of the workpiece is polished.
[0003]
[Problems to be Solved by the Invention]
The dressing process for the gear honing grindstone uses a dress gear (master gear) having the same shape as the gear-shaped workpiece and electrodeposited with diamond abrasive grains on the surface. The dressing gear is used for dressing. When a large processing load, i.e. stress or frictional heat, concentrates on the tooth tip of the dress gear, and the diamond abrasive grains on the tooth tip tend to fall off or peel off at an early stage, so that the durable life of the dress gear cannot be obtained sufficiently was there.
[0004]
On the other hand, as described in Japanese Patent Laid-Open No. 10-337615, attempts have been made to embed a reinforcing material such as a synthetic resin in the relief groove, and a temporary result has been obtained. In addition, the cost of embedding resin becomes a problem. Relief grooves cut by a predetermined distance in the radial direction are provided between the inner peripheral teeth of the gear honing grindstone, and the processing load applied to the tooth tip of the dress gear during dressing processing is reduced. However, the gear honing grindstone in which the clearance grooves are provided between the inner peripheral teeth as described above, especially when performing high-efficiency machining using superabrasive grains, the inner peripheral teeth Since the strength of the base portion of the base plate is lowered and the base portion is easily deformed in the circumferential direction and the radial direction, the interval between the inner peripheral teeth is changed in the dressing process and the honing process, and the dressing accuracy and the honing accuracy may not be obtained. On the other hand, in recent manufacturing sites, gear materials are becoming harder and harder to improve gear accuracy and durability, and further reductions in pretreatment processes are being studied to improve productivity and reduce costs. The machining allowance in processing is increasing.
[0005]
The present invention has been made in the background of the above circumstances, and the object of the present invention is a gear capable of obtaining a durable life, dressing accuracy and honing accuracy of a dressing gear used for dressing processing while having high efficiency and long life. It is to provide a honing grindstone.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the gist of the first invention is to provide a honing grindstone for a gear having a plurality of teeth for meshing with the gear surface in order to polish the tooth surface of the gear. The softening of the plurality of teeth toward the tooth base is more likely than the tooth tip.
[0007]
[Effect of the first invention]
In this way, the honing grindstone for a gear according to the present invention has a shape similar to that of a gear-shaped workpiece because the hardness of the abrasive grains is made softer toward the tooth base than the cutting edges of the plurality of teeth. When dressing is performed by meshing a dress gear with diamond abrasive grains electrodeposited on the surface, the tooth tip of the dress gear contacts and slides on the tooth base that is softer than the tooth tip of the gear honing wheel. Therefore, even if a large processing load, i.e., stress or frictional heat, is concentrated on the tooth tip of the dress gear, it is possible to prevent the diamond abrasive grains from dropping off or peeling off at the tip of the dress gear, and to sufficiently obtain the durable life of the dress gear. . Further, since the durable life of the dress gear can be obtained without providing escape grooves between the teeth of the gear honing grindstone, the decrease in dressing accuracy and honing accuracy due to the escape grooves is preferably eliminated.
[0008]
[Second means for solving the problem]
In order to achieve the above object, the gist of the second invention is a gear honing grindstone having a plurality of teeth for meshing with a gear to grind the tooth surface of the gear, and (a) a superabrasive A main body having abrasive grains softer than the grains, and (b) a tooth portion including superabrasive grains and projecting radially from a plurality of locations in the circumferential direction on the peripheral surface of the main body. , To include.
[0009]
[Effect of the second invention]
In this way, the honing grindstone for a gear according to the present invention has a plurality of teeth including superabrasive grains in the circumferential direction on the peripheral surface of the main body having abrasive grains softer than the superabrasive grains. When the dressing gear in which diamond abrasive grains are electrodeposited on the surface of the same shape as the gear-shaped workpiece is meshed and dressing is performed, the teeth of the dressing gear are formed. Since the tip contacts the main body with the abrasive grains softer than the superabrasive grains and slides on it, even if a large processing load, i.e. stress or frictional heat, is concentrated on the tip of the dress gear, The falling or peeling of the diamond abrasive grains on the tooth tip is suitably prevented, and the durable life of the dress gear can be sufficiently obtained. Further, since the durable life of the dress gear can be obtained without providing escape grooves between the teeth of the gear honing grindstone, the decrease in dressing accuracy and honing accuracy due to the escape grooves is preferably eliminated. Furthermore, since it is not necessary to use expensive superabrasive grains other than the tooth portion, the cost can be reduced.
[0010]
Other aspects of the invention
Here, preferably, the honing grindstone for a gear has an annular main body and a plurality of inner peripheral teeth projecting radially from a plurality of locations in the circumferential direction on the inner peripheral surface of the main body. . If it does in this way, a honing process will be given with respect to the gear provided with the outer periphery tooth | gear.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 is a perspective view showing the entirety of an internal tooth type honing grindstone 10 used for gear honing in one embodiment of the present invention. The internal tooth type honing grindstone 10 has a ring shape as a whole, and is formed with dimensions such as an outer diameter of about 300 mm, an inner diameter of about 250 mm, and a width (length in the axial direction) of about 40 mm. For example, as shown in FIG. 2, the internal gear type honing grindstone 10 includes a ring-shaped main body 12 whose main abrasive is softer than superabrasive grains, and a circumferential direction on the inner peripheral surface of the main body 12. And a plurality of inner peripheral tooth portions 14 each having a superabrasive grain as a main abrasive grain. The inner peripheral teeth 14 are, for example, a plurality of helical teeth that are inclined at a predetermined angle with respect to the axial direction. The inner peripheral tooth portion 14 is formed so that, for example, m (module) is 2.0, P (pressure angle) is 17.5, and Z (number of teeth) is 120. The inner diameter of the internal tooth type honing grindstone 10 is the diameter of the cylindrical surface passing through the tooth tip of the inner peripheral tooth portion 14.
[0013]
The main body 12 is formed by bonding fused alumina-based white alundum (WA) abrasive grains of about # 180, for example, with a thermosetting resin such as an epoxy resin so as to have a bonding degree R and a structure 7 (WA180R7Y For example, having an elastic modulus of about 1 to 50 GPa and a thermal expansion coefficient of about 25 × 10 ⁻⁶ / ° C. As the elastic modulus, that is, the kind of binder, a material suitable for gear honing is selected. In addition, the inner peripheral tooth portion 14 is composed of a mixture of CBN abrasive grains (30%) of about # 180 and WA abrasive grains (70%), for example, by a thermosetting resin such as an epoxy resin, a bonding degree R, and a structure 7 (CBN180R7Y) that is connected so that Thereby, on the inner peripheral surface of the internal tooth type honing grindstone 10, the main body portion 12 exclusively containing WA abrasive grains is exposed at the bottom of the tooth groove 16.
[0014]
For example, as shown in FIGS. 3 (a) and 3 (b), the internal gear honing grindstone 10 is polished to obtain a predetermined shape accuracy of the helical gear 18 that is a workpiece after quenching. That is, it is used for honing. In FIG. 3 (a), a helical gear 18 as a work material is attached to a rotating shaft 20 supported at both ends (not shown) so as not to rotate relative to each other in the axial direction and the circumferential direction. Then, when the rotary shaft 20 is driven by a drive mechanism (not shown), the helical gear 18 is rotated around its axis and reciprocated in the axis direction. On the other hand, the internal tooth type honing grindstone 10 has its axial center in the axial direction of the rotary shaft 20 as shown in FIG. 3A so that the internal peripheral tooth portion 14 meshes with the external peripheral tooth of the helical gear 18. The shaft center is inclined at a predetermined angle with respect to the shaft center of the helical gear 18 as shown in FIG. 3B. The outer peripheral surface is attached to a holder or the like (not shown) so as to be rotatable about its axis, and is rotated along with the rotation of the helical gear 18 while maintaining the meshing state. As a result, the shape of the inner peripheral tooth portion 14 of the internal gear honing grindstone 10 is transferred to the helical gear 18 to improve the shape accuracy.
[0015]
Since the inner peripheral tooth portion 14 of the internal tooth type honing grindstone 10 includes CBN abrasive grains, the above honing process doubles the cutting amount compared to the conventional internal tooth type honing grindstone using general abrasive grains. That is, since it can be set to about 0.1 mm, a processing efficiency of about double is obtained. Further, since the shape deformation of the inner peripheral tooth portion 14 is small, the dress interval can be increased 1.5 times from the conventional 30 / D to 50 / D.
[0016]
By the way, also in the above-described internal tooth type honing grindstone 10, when the inner peripheral tooth portion 14 of the main body portion 12 is worn, it is necessary to sharpen and correct the shape using a dresser. For example, in FIGS. 3 (a) and 3 (b), a dress gear (dresser) in which diamond abrasive grains are electrodeposited on the surface of the same shape is attached to the rotary shaft 20 instead of the helical gear 18. is there. At this time, the dress gear is operated so as to press the inner peripheral surface of the internal gear honing grindstone 10 in order to give an appropriate cutting amount, and the inner peripheral surface and the inner peripheral tooth portion 14 are compared toward the outer peripheral side. Large stress acts.
[0017]
According to the present embodiment, in the dressing process described above, the tooth tip that is most easily damaged among the dress gears having the same outer shape as the helical gear 18 and electrodeposited with diamond abrasive grains is the inner peripheral tooth. Since the main body portion 12 containing abrasive grains softer than the portion 14 is brought into contact with and slidably contacted with the main body portion 12, even if a large processing load, that is, stress or frictional heat is concentrated on the tooth tips of the dress gear, Can be prevented from falling off or peeling off, and the durable life of the dress gear can be sufficiently obtained. Further, since the durable life of the dress gear can be obtained without providing escape grooves between the teeth of the gear honing grindstone, the decrease in dressing accuracy and honing accuracy due to the escape grooves is preferably eliminated.
[0018]
As mentioned above, although one Example of this invention was described in detail with reference to drawings, this invention is applied also in another aspect.
[0019]
For example, in the above-described embodiment, the inner peripheral tooth portion 14 of the internal tooth type honing grindstone 10 is a mixed abrasive in which CBN abrasive grains and molten alumina abrasive grains are mixed at a ratio of 3: 7, and the main body. Although the WA abrasive grains having a lower hardness as a whole than the mixed abrasive grains were used for the portion 12, the hardness of the abrasive grains contained therein gradually increased from the tip of the inner peripheral tooth portion 14 toward the tooth base. Alternatively, it may be continuously lowered (soft).
[0020]
In addition, the inner peripheral tooth portion 14 of the above-described embodiment was a whole containing mixed abrasive grains in which CBN abrasive grains and fused alumina abrasive grains were mixed at a ratio of 3: 7. Only a thickness of 5 to 8 mm from the surface, for example, the surface of the surface may comprise the mixed abrasive grains. The internal gear honing grindstone 10 gradually increases in inner diameter by being dressed, and at this time, changes in a direction in which the twist angle increases. For this reason, the accuracy of the tooth surface of the helical gear 18 that is a work material gradually deteriorates. Therefore, the amount of expansion of the inner diameter, that is, the usage fee of the inner peripheral tooth portion 14 is, for example, when the initial inner diameter is 250 mm. This is because the upper limit is about 5 to 8 mm in radius.
[0021]
Moreover, in the Example, the mixed-abrasive particle | grains by which the CBN abrasive grain and the molten alumina abrasive grain were mixed by the ratio of 3: 7 were used for the internal peripheral tooth part 14 of the said internal gear type honing grindstone 10. However, the mixing ratio can be appropriately changed as necessary mainly to achieve both the honing performance, the price, and the life of the dressing gear. Generally, the mixing ratio of superabrasive grains to all abrasive grains is selected within a range of 5% to 95%. If it is less than 5%, the dressing property is improved, but the grinding efficiency and the grinding wheel life are deteriorated, and the dressing interval is shortened and the efficiency is lowered. On the other hand, if it exceeds 95%, the grinding efficiency and the wheel life are improved and the dress life is extended, while the dressability is deteriorated and cannot be corrected to the worst specified shape. The range is preferably 10 to 50%, and more preferably 15 to 40%. However, when the degree of bond and strength of thermosetting resins such as phenol and epoxy are relatively small, CBN abrasive grains and diamond abrasive grains may be used alone. Moreover, although the molten alumina type abrasive grain was used for the main-body part 12 of the said internal gear type honing grindstone 10, the kind of abrasive grain is not specifically limited. For example, eutectic alumina / zirconia abrasive grains, microcrystalline sintered alumina abrasive grains, sintered alumina abrasive grains, silicon carbide abrasive grains, or the like may be used. In short, it is sufficient that the abrasive grains are softer as a whole than the abrasive grains of the inner peripheral tooth portion 14. For example, in the case where a mixed abrasive in which CBN abrasive and molten alumina abrasive are mixed at a ratio of 3: 7 is used for the inner peripheral tooth portion 14, the CBN abrasive and molten alumina abrasive are 1: 9. Mixed abrasive grains mixed at a ratio may be used for the main body 12.
[0022]
Further, in the embodiment, the case where the present invention is applied to the internal tooth type honing grindstone 10 having the helical inner peripheral tooth portion 14 for processing the helical gear 18 has been described. An external tooth type honing grindstone provided may be used.
[0023]
In addition, although not illustrated one by one, the present invention can be variously modified without departing from the spirit of the present invention.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view showing an entire internal gear honing stone according to an embodiment of the present invention.
FIG. 2 is an enlarged view illustrating a part of the internal tooth type honing grindstone of FIG. 1, that is, an inner peripheral tooth.
FIG. 3 is a diagram for explaining a state in which a gear is honed using the internal tooth grindstone of FIG. 1, wherein (a) is a cross-sectional view taken along line aa in (b) parallel to the axial direction; b) is a view showing a cross section perpendicular to the axial direction.
[Explanation of symbols]
10: Internal tooth type honing wheel (Honing wheel for gears)
12: Body part 14: Inner peripheral tooth part

Claims (2)

In a gear honing grindstone having a plurality of teeth for meshing with the gear to grind the tooth surface of the gear,
A honing grindstone for gears, characterized in that the hardness of the abrasive grains becomes softer toward the tooth base than the tooth tips of the plurality of teeth. A honing grindstone for a gear having a plurality of teeth for meshing with the gear to grind the tooth surface of the gear,
A main body having a softer abrasive grain than the superabrasive grain as the main abrasive grain;
A gear honing grindstone comprising superabrasive grains and tooth portions projecting radially from a plurality of locations in the circumferential direction on the circumferential surface of the main body.

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