JPH0724711A - Grinding method for center hole - Google Patents

Abstract

PURPOSE:To increase the circularity of a center hole by providing a difference between a dresser locus angle and a grinding wheel oscillation locus angle, and synchronizing the planetary motion of a grinding wheel shaft with a specified or more integer times of reciprocation of grinding wheel oscillation motion for each rotation of the grinding wheel shaft. CONSTITUTION:An angle alpha of a dresser locus A relative to the centerline L1 of a grinding wheel shaft 12 is set at, for example, 30 deg., a locus angle beta of an oscillation locus B of the grinding wheel 11 relative to the centerline L1 of the grinding wheel shaft 12 is set at, for example, 29.5, and a difference of 0.5 deg. is provided between these locus angles alpha and beta. Then, using a cam mechanism, the planetary motion of the wheel shaft 12 is synchronized so that the oscillation motion is reciprocated by three or more integer times for each rotation of the wheel shaft 12. When a center hole 13 is ground by a grinding wheel 11 with this constitution, the wheel 11 located at T1 point shown by solid line is moved by 60 deg. to an imaginary line at T2 point. Thus the center hole 13 is formed in a toroidal shape. Then the wheel 11 touches at three points, and the planetary motion accuracy of the wheel shaft 12 in roundness can be maintained without being affected by grinding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for grinding a center hole, which is carried out prior to cylindrical grinding of a work.

[0002]

2. Description of the Related Art Grinding of a center hole is conventionally performed with reference to FIGS.
The rotation of the grindstone 1, the planetary movement of the grindstone shaft 2 about the center line L of the center hole 3, and the oscillation of the grindstone 1 along the angle of the center hole 3 provided in the work W as shown in FIG. The movements were simultaneously performed as independent movements.

However, since the roundness of the center hole 3 is greatly affected by the precision of the planetary movement of the grindstone shaft 2, if there is a problem in the precision of the planetary movement of the grindstone shaft 2, the center hole of poor roundness may result. turn into. Poor roundness of the center hole adversely affects the accuracy of the subsequent cylindrical grinding, so it is necessary to ensure the roundness of the center hole.

[0004]

The problem to be solved by the present invention is, in the grinding of the center hole, not affected by the accuracy of the planetary motion of the grindstone shaft centering on the center line of the center hole. To ensure roundness.

[0005]

[Means for Solving the Problems] The dresser locus angle and the grindstone oscillation locus angle are made different from each other, and 3 of the grindstone oscillation motions are made for one revolution of the planetary motion of the grindstone shaft.
Synchronize the above integer round trips.

[0006]

The difference between the dresser locus angle α and the grindstone oscillation locus angle β in FIG. 1 is Δα. Wheel axis 12
For example, one revolution of the planetary movement of 3 synchronizes three reciprocations of the oscillation movement of the grindstone 11.

If the oscillation movement distance of the grindstone 11 at the time T1 and the time T2 is ΔF and the difference between the center A of the center hole 13 and the points A and B is ΔS, then ΔS = ΔF · SINΔα / COSα, the center hole 13 has a trochoidal shape as shown in FIG. 3, and the whetstone 11 comes into contact with the center hole 13 at three points. Therefore, the accuracy of the planetary movement of the grindstone shaft 12 is not affected by the grinding of the center hole 13.

[0008]

EXAMPLE In FIG. 3, 11 is a grindstone having a conical grinding surface, and 12 is a grindstone shaft. A dresser 14 reciprocates in the direction a in the figure to dress the grindstone 11.

The angle of the locus A of the dresser 14 with respect to the center line L1 of the grindstone shaft 12, that is, the dresser locus angle α in the embodiment is 30 °, which is a general angle of the center hole 13. The angle of the oscillation locus B of the grindstone 11 with respect to the center line L1 of the grindstone shaft 12, that is, the grindstone oscillation locus angle β is 29.5 °, and the difference between the dresser locus angle α and the grindstone oscillation locus angle β. Δα is 0.5 ° and is formed by grinding the grindstone 11.

The grindstone 11 rotates about the centerline L1 of the grindstone shaft 12 and makes a planetary movement about the centerline L2 of the center hole 13 of the work W as an axis. At the same time as this planetary movement, the grindstone 11 makes an oscillation movement. In the embodiment, a cam mechanism is used to synchronize the oscillation motion with three reciprocations per one rotation of the planetary motion.

Then, as shown in FIG.
When grinded by No. 1, the grindstone 11 at the point T1 shown by the solid line
Is at the position indicated by the imaginary line at the point T2, and moves 60 ° as shown in FIG. As a result, the center hole 13 is formed in a trochoid shape, and the contact with the center hole 13 is at three points, so that the roundness can be secured without the grinding being influenced by the accuracy of the planetary movement of the grindstone shaft 12.

It is also possible to synchronize the oscillation motion with three or more reciprocations, for example, five reciprocations, per planetary revolution of the grindstone 11. Also, the dresser locus angle α
And the grindstone oscillation trajectory angle β can be arbitrarily selected.

[0013]

EFFECTS OF THE INVENTION It is possible to perform highly accurate center hole grinding that is not affected by the accuracy of the planetary motion of the grindstone shaft.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a grinding state of the present invention.

FIG. 2 is a plan view of a center hole during grinding according to the present invention.

FIG. 3 is an explanatory diagram showing a dresser trajectory angle and a grindstone oscillation angle.

FIG. 4 is an explanatory diagram showing a conventional grinding method.

FIG. 5 is a plan view of a center hole during grinding by a conventional grinding method.

[Explanation of symbols]

11 grindstone 12 grindstone shaft 13 center hole α dresser locus angle β grindstone oscillation locus angle Δα difference between dresser locus angle and grindstone oscillation locus angle

Claims (2)

[Claims] 1. Grinding of a center hole by rotation of the grindstone, planetary movement of the grindstone axis around the center line of the center hole, and oscillation movement of the grindstone along the angle of the center hole.
The center hole grinding is characterized in that the dresser locus angle and the grindstone oscillation locus angle are made different from each other, and three or more integer reciprocations of the grindstone oscillation motion are synchronized for one revolution of the planetary movement of the grindstone shaft. Method. 2. The method for grinding a center hole according to claim 1, wherein the whetstone oscillation movement is three reciprocations.