JP7246338B2 - Work grinding method and shoe type centerless grinding machine - Google Patents

Description

The present invention is a cylindrical body having a continuous cylindrical portion formed continuously in the circumferential direction on the end side in the axial direction, and a discontinuous cylindrical portion formed discontinuously in the circumferential direction in addition to the continuous cylindrical portion. and a shoe-type centerless grinder used for grinding.

When grinding the outer diameter of a workpiece such as a cylindrical body having a continuous cylindrical portion formed continuously in the circumferential direction and a discontinuous cylindrical portion formed discontinuously in the circumferential direction using a centerless grinder If the work has two or more continuous cylindrical parts in the axial direction, it can be ground by a through-feed type centerless grinder, and a centerless grinder as described in Cited Document 1 can be used. Outer diameter grinding is possible even if it is used.

The centerless grinder described in Cited Document 1 is intended for grinding a workpiece having continuous cylindrical portions on both axial end sides, and is equipped with two sets of shoes corresponding to the respective continuous cylindrical portions of the workpiece. The two sets of shoes support the workpiece so as to be rotatable about its center.

JP-A-08-229813

Workpieces such as cylindrical bodies have various shapes and structures depending on their use. In the case of a work having a continuous cylindrical portion only on one end side in the axial direction, such as a work whose entirety is a discontinuous cylindrical portion, the outer diameter cannot be ground.

If the workpiece has a continuous cylindrical portion only on one end side, the continuous cylindrical portion side of the workpiece is attracted to the end face side of the spindle by an electromagnetic chuck in the spindle, and the continuous cylindrical portion is held by a shoe placed near the end face side of the spindle. It is also conceivable to grind the outer diameter in a state in which the part is supported from the outer peripheral side, so to speak, in a cantilevered state.

However, when grinding the outer diameter of a workpiece, a large grinding load is applied to the tip side of the workpiece. There are problems such as the need for a strong electromagnetic chuck that can be sufficiently maintained.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a work grinding method and a shoe-type centerless grinder capable of safely grinding the outer diameter of a work while preventing the work from falling off during grinding. do.

In the method of grinding a workpiece according to the present invention, a cylindrical workpiece that is attracted to the end face of a spindle by an electromagnetic chuck and rotatably supported by a shoe is rotated, and the workpiece is ground through the first grinding step and the second grinding step. When grinding the outer diameter of a work with a grindstone, the work is inserted into the outer periphery of a fall prevention pin that is rotatable integrally with the spindle, and the fall prevention pin limits the fall of the work during grinding . In the first grinding step, due to the grinding load of the grindstone, the workpiece falls down in the gap between the workpiece and the tipping prevention pin against the adsorption force of the electromagnetic chuck. In the 2nd grinding step, the work is returned to a chucked state substantially parallel to the fall-preventing pin against the grinding load of the grindstone by the chucking force of the electromagnetic chuck.

The shoe may support the vicinity of the suction side of the work from the outer peripheral side. It is desirable that the gap between the work and the fall prevention pin is a very small gap. It is desirable that the fall prevention pin is a non-magnetic material .

The work includes a continuous cylindrical portion formed continuously in the circumferential direction at the end on the side of attraction by the electromagnetic chuck, and a discontinuous cylindrical portion formed discontinuously in the circumferential direction other than the continuous cylindrical portion. It may be a cylindrical body having

A shoe-type centerless grinder according to the present invention performs a first grinding process and a second grinding process while rotating a cylindrical workpiece that is attracted to the end surface of a spindle by an electromagnetic chuck and rotatably supported by a shoe. A shoe-type centerless grinder for grinding the outer diameter of the work with a grindstone, comprising a fall prevention pin that is rotatably provided integrally with the main shaft and that restricts the fall of the work inserted into the outer circumference , In the first grinding step, the work falls down in the gap between the work and the fall prevention pin against the adsorption force of the electromagnetic chuck due to the grinding load of the grindstone. In the second grinding step, due to the attraction force of the electromagnetic chuck, the whetstone returns to the attraction state substantially parallel to the fall prevention pin against the grinding load of the grindstone.

It is preferable that the shoe supports the workpiece near the suction side from the outer circumference, and the fall prevention pin is coaxial with the center of the main shaft.

According to the present invention, the workpiece is inserted into the outer periphery of the fall prevention pin that can rotate integrally with the spindle, and the fall prevention pin limits the fall of the workpiece during grinding. There is an advantage that the outer diameter of the work can be ground safely.

1 is a perspective view of a workpiece to be ground; FIG. It is a front sectional view showing one embodiment of the present invention. It is the same side sectional view. It is explanatory drawing of the same fall amount measurement. It is explanatory drawing at the time of the rough grinding. It is explanatory drawing at the time of the same finish grinding.

An embodiment of the invention will be described in detail below with reference to the drawings. FIG. 1 shows a workpiece W to be ground. This workpiece W is a cylindrical body having an axial cutout portion 1 formed in a range excluding one end side in the axial direction, and a continuous cylindrical portion 2 formed continuously in the circumferential direction at the one end side in the axial direction. and a discontinuous cylindrical portion 3 formed discontinuously in the circumferential direction in a range excluding this continuous cylindrical portion 2 . The discontinuous cylindrical portion 3 is discontinuous in the circumferential direction due to the axial notch portion 1 formed in a part of the circumferential direction.

The work W may be a cylindrical body having the continuous cylindrical portion 2 over substantially the entire length in the axial direction, or may be provided with the continuous cylindrical portions 2 at a plurality of locations in the axial direction. Therefore, the workpiece W is a cylindrical body as shown in FIG. It is not limited to cylindrical bodies. In addition, the discontinuous cylindrical portion 3 may have notches 1 or openings at a plurality of locations in the circumferential direction.

2 shows a front sectional view of the shoe type centerless grinder 10, and FIG. 3 shows a side sectional view of the shoe type centerless grinder 10. As shown in FIG. As shown in FIGS. 2 and 3, the centerless grinder 10 comprises a main shaft 11 supported rotatably about a horizontal axis, and a work suction member coaxially fixed to the end face of the main shaft 11 and having a work W attached thereto. 12, a fall prevention pin 15 which is fixed coaxially with the main shaft 11 to the suction surface 13 of the work suction body 12 and which restricts the fall of the work W inserted to the outer peripheral side through the gap 14 from the inside; a front shoe 16 and a rear shoe 17 that rotatably support the vicinity of the work attracting body 12 side of the work attracting body 12; It has

An electromagnetic chuck 20 is built in the spindle 11, and the end surface of the workpiece W inserted into the outer periphery of the fall prevention pin 15 is attracted to the attraction surface 13 of the workpiece attractor 12 by the electromagnetic attracting force of the electromagnetic chuck 20. As the main shaft 11 rotates, the work W is rotated around the work center W0.

The fall prevention pin 15 is for restricting the fall of the work W from the inside during the first grinding process such as rough grinding in which the grinding load of the grindstone 18 is larger than the attraction force of the electromagnetic chuck 20. It is composed of a cylindrical body with a diameter slightly smaller than the inner diameter, and is fixed to the attraction surface 13 of the work attraction body 12 via mounting means 15a such as screws. The workpiece W is inserted on the outer periphery of the fall prevention pin 15 with a minute gap therebetween. The length of protrusion of the fall prevention pin 15 from the workpiece attracting body 12 is approximately the same as the length of the workpiece W in the axial direction, but it may be slightly longer or shorter than the workpiece W. In that case, it is better to decide according to the loading form of the workpiece W and the like.

The workpiece attracting body 12 is made of a magnetic material so that the workpiece W can be attracted by the electromagnetic force of the electromagnetic chuck 20 . However, even when the work W is attracted to the work attracting body 12 by the electromagnetic force of the electromagnetic chuck 20 , the fall prevention pin 15 is designed so that the work W is not attracted to the outer peripheral surface of the fall prevention pin 15 by the electromagnetic force. It is composed of a magnetic material. Therefore, the work W can be rotated around the work center W0 on the outer periphery of the fall prevention pin 15 even in a state where the work W is attracted to the work attracting member 12 by the attracting force of the electromagnetic chuck 20 .

The front shoe 16 is arranged below the work W, and the rear shoe 17 is arranged on the opposite side of the work W from the grindstone 18 . The front shoe 16 and the rear shoe 17 are attached to a mount 19 so that their positions can be adjusted in directions 16a and 17a passing through the center of the work W. By appropriately adjusting the front shoe 16 and the rear shoe 17, the work center W0 is set so as to be slightly eccentric to the grindstone 18 side below the pin center (=main shaft center) C1 of the fall prevention pin 15 .

As a result, when the main shaft 11 rotates, it is possible to rotate the work W around the work center W0 while pressing the work W against the front shoe 16 and the rear shoe 17 in synchronization with the rotation of the main shaft 11. It can be stably rotated around the center W0.

That is, when the spindle 11 rotates, the work center W0 tries to rotate around the spindle center C1 with a radius equal to the amount of eccentricity from the spindle center C1. However, since the front shoe 16 and the rear shoe 17 are in contact with the outer circumference of the work W, and the shoes 16 and 17 serve as stoppers for the work W, the work W cannot rotate around the spindle center C1. As a result, the force that presses the work W against the front shoe 16 and the rear shoe 17 continues to be generated, and the work W can be rotated around the work center W0 on the basis of the outer diameter.

At this time, since the workpiece W is eccentric with respect to the spindle center C1, it slides on the adsorption surface 13 of the workpiece adsorption body 12 in the eccentric direction and rotates around the workpiece center W0 on the basis of the outer diameter. .

The fall prevention pin 15 must have the following outer diameter. D is the pin outer diameter of the fall prevention pin 15, d is the inner diameter of the work W, A is the vertical eccentricity between the work center W0 and the pin center (main shaft center) C1, and the work center W0 and the pin center (main shaft center) C1 When the amount of eccentricity in the grinding wheel direction is B, the pin maximum outer diameter Dmax of the fall prevention pin 15 is given by formula 1), and the pin minimum outer diameter Dmin is given by formula 2), so the pin outer diameter of the fall prevention pin 15 D is the formula 3).
Pin maximum outer diameter Dmax<d-2√(A2+B2) ・・・1) Formula Pin minimum outer diameter Dmin>d-2C ・・・2) Formula d-2C<Pin outer diameter D<d-2√ (A2 + B2) ・・・・3) Formula

When adjusting the front shoe 16 and the rear shoe 17, the amount of eccentricity in the vertical direction between the work center W0 of the finished dimensions of the work W and the pin center (main shaft center) C1 is A, and the work center W0 and the pin center (main shaft center C1) are aligned. is adjusted so that the amount of eccentricity in the direction of the grindstone is B. When the main shaft 11 rotates rightward (clockwise) in the direction of arrow f in FIG. The amounts of eccentricity A and B are determined by the size of the workpiece W and the grinding allowance.

Since the fall prevention pin 15 must not come into contact with the inner diameter of the work W when the work W is inserted into the outer periphery of the fall prevention pin 15, the outer diameter of the fall prevention pin 15 is closer to the work center W0 than the inner diameter of the work W. and the pin center C1 by the amount of eccentricity (√(A ² +B ² )). Therefore, the pin maximum outer diameter Dmax of the fall prevention pin 15 is made smaller than the value obtained by subtracting twice the amount of eccentricity from the inner diameter d of the workpiece, as shown in formula 1).

On the other hand, as shown in FIG. 4, the work W is rotated clockwise in the direction of arrow f without the fall prevention pin 15, and the cutting direction of the grindstone 18 is applied to the tip side of the work W opposite to the work attracting body 12. While applying a load to 18a, the amount of inclination until the work W falls off against the adsorption force of the electromagnetic chuck 20 is measured.

When the workpiece W is pushed in the cutting direction 18a of the grindstone 18 and the amount of inclination reaches C, assuming that the workpiece W falls off the workpiece attracting body 12, the amount of inclination C is half the diameter. Therefore, the pin minimum outer diameter Dmin of the fall prevention pin 15 is made larger than the value obtained by subtracting the diameter 2C from the inner diameter d of the workpiece, as shown in equation 2). It should be noted that the tilt amount C varies depending on the magnitude of the attraction force of the electromagnetic chuck 20 .

As a result of these formulas 1) and 2), when a large grinding load L1 is applied to the work W in the direction of cutting (indicated by arrow g) as shown in FIG. 6, and when the grinding load L2 in the direction of cutting into the workpiece W (indicated by the arrow g) decreases as shown in FIG. In order to allow the workpiece W to be re-adsorbed to the workpiece attracting body 12 against L2, it is necessary to use a thickness of the anti-falling pin 15 that satisfies the formula 3).

The grindstone 18 can reciprocate with respect to the work W in a direction passing through the work center W0. The thickness of the grindstone 18 in the axial direction is greater than or equal to the length of the workpiece W in the axial direction.

When grinding the outer diameter of the work W, as shown in FIG. The circumference is attracted to the attraction surface 13 of the workpiece attraction body 12 . It is safe to use a robot or the like to insert the workpiece W into the outer periphery of the fall prevention pin 15 .

When the spindle 11 is rotated clockwise in the direction indicated by the arrow f, the workpiece center W0 is eccentric downward with respect to the spindle center C1 by a predetermined amount of eccentricity on the grindstone 18 side. The continuous cylindrical portion 2 is pressed by the front shoe 16 and the rear shoe 17 while being attracted to the workpiece attracting member 12 by force, and rotates clockwise around the workpiece center W0 in synchronization with the rotation of the main shaft 11. - 特許庁At this point, the workpiece W is not in contact with the fall prevention pin 15. As shown in FIG.

In the first grinding step, the grindstone 18 rotating in the direction indicated by h is cut from the grinding start position toward the workpiece W at a high rough grinding speed in the direction indicated by the arrow g. Rough grind the outer diameter.

In this first grinding step, when rough grinding is started by cutting the grindstone 18 into the work W at a rough grinding speed, the work chuck 20 is attracted to the work chuck 12 by the electromagnetic force of the electromagnetic chuck 20. As shown in FIG. 5, a large grinding load L1 of the grindstone 18 is applied to the workpiece W supported by the shoes 16 and 17 in the cutting direction at a position away from the shoes 16 and 17. , the workpiece W is separated from the adsorption surface 13 of the workpiece adsorption body 12 and tilted.

However, since the work W has the fall prevention pin 15, the work W only falls within the range of the gap 14 between the work W and the fall prevention pin 15. is in contact with the attracting surface 13 of the work attracting body 12, the work W is attracted by the electromagnetic force of the electromagnetic chuck 20 in a tilted state, and does not come off the work attracting body 12. - 特許庁Therefore, the rough grinding of the workpiece W can be continued in the fallen state.
Note that the tilt angle of the work W does not affect the rough grinding of the outer diameter of the work W because the gap between the work W and the tilt prevention pin 15 is very small.

After the first grinding process is completed, the second grinding process is started to cut the rotating grindstone 18 at a finish grinding speed lower than the rough grinding speed. In this second grinding process, since the grindstone 18 cuts into the work W at a slow finish grinding speed, the grinding load L2 of the grindstone 18 with respect to the work W becomes small, and the adsorption force of the electromagnetic chuck 20 becomes larger than the grinding load L2. Therefore, as shown in FIG. 6, the entire circumference of the end face of the continuous cylindrical portion 2 of the workpiece W is attracted to the workpiece attracting body 12, returning to the normal attracting state.

In the second grinding step, after performing the finish grinding of the work W in a normal suction state, the movement of the grindstone 18 is stopped and spark out is performed while the grindstone 18 is rotating, and then grinding of the grindstone 18 in the rotating state is started. The work W is returned to the position in the direction of the arrow g, the adsorption of the work W by the electromagnetic chuck 20 is released, and the work W after grinding is pulled out from the outer periphery of the fall prevention pin 15 . Thus, a series of operations for grinding the outer diameter of the work W is completed. In the second grinding step, the outer diameter of the workpiece W is ground in parallel with the central axis through finish grinding and spark-out, and finished to the required grinding accuracy.

If such a method for grinding the work W is adopted, the work W may fall down and jump out during grinding, even though the work W is a cylindrical body having the continuous cylindrical portion 2 only on one end side in the axial direction. Therefore, the work W can be ground to the required grinding accuracy while improving safety.

Also, damage to the shoes 16 and 17 and the grindstone 18 due to the falling off of the workpiece W during grinding can be prevented. Furthermore, since the main shaft 11 and the fall prevention pin 15 rotate integrally, it is possible to prevent the work W from being damaged due to poor rotation.

In the first grinding process where a larger grinding load L1 is applied, the work W falls down, and in the second grinding process where a smaller grinding load L2 is applied after that, the work W can return to a normal suction state, so a large grinding load is applied. Even in the first grinding step in which L1 is applied, it is not necessary to use a strong electromagnetic chuck 20 that keeps the workpiece W in a normal chucking state at all times, and the size of the apparatus can be reduced.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments, and various modifications can be made without departing from the scope of the invention. The electromagnetic chuck 20 built into the spindle 11 can maintain a suction state so that the workpiece W does not fall off in the first rough grinding step of rough grinding. Any electromagnetic force may be used as long as it can attract the workpiece W in a normal state and allows eccentric rotation with respect to the workpiece attracting body 12 .

When the fall prevention pin 15 is indirectly or directly provided on the end face side of the main shaft 11 via the workpiece attracting body 12, it is desirable to provide the mounting means 15a on the pin center C1 of the fall prevention pin 15. Other means may be used instead of 15a.

It is desirable that the shoes 16 and 17 support the workpiece W in the vicinity of the adsorption surface 13 of the workpiece adsorption body 12 from the outer peripheral side. The shoes 16 and 17 can be arranged at a position slightly away from the adsorption surface 13 of the workpiece adsorption body 12 if the work adsorption body 12 falls while contacting the adsorption surface 13 of the workpiece adsorption body 12 .

The gap 14 between the work W and the fall prevention pin 15 is basically a minute gap, but the size of the gap 14 depends on the size of the adsorption force of the electromagnetic chuck 20, the length of the work W, and the fall prevention pin. It is necessary to consider the length of 15, etc., and determine it concretely. For example, if the length of the workpiece W is longer than the collapse prevention pin 15, the gap 14 needs to be made small.

The amount of eccentricity between the work center W0 and the spindle center (pin center) C1 is such that the work W rotates around the work center W0 while the work W is pressed against the shoes 16 and 17 by the rotation of the main spindle 11. It is enough if it can be rotated.

Further, in the embodiment, rough grinding is divided into rough grinding and finish grinding, and the rough grinding is the first grinding step, and the finish grinding is the second grinding step. It is also possible to appropriately change the combination according to the magnitude of the grinding load, such as one grinding process and intermediate grinding and subsequent finish grinding as the second grinding process.

W work 2 continuous cylindrical part 3 discontinuous cylindrical part 10 shoe type centerless grinder 11 main shaft 12 workpiece attracting body 13 attracting surface 14 gap 15 fall prevention pin 16 front shoe 17 rear shoe 18 grindstone 20 electromagnetic chuck

Claims (7)

When grinding the outer diameter of a cylindrical workpiece with a grindstone through a first grinding step and a second grinding step while rotating a cylindrical workpiece that is attracted to the end face side of the spindle by an electromagnetic chuck and rotatably supported by a shoe. ,
inserting the work into the outer circumference of a fall prevention pin that can rotate integrally with the main shaft, and restricting the fall of the work during grinding by the fall prevention pin;
In the first grinding step, due to the grinding load of the grindstone, the workpiece falls down in the gap between the workpiece and the fall prevention pin against the adsorption force of the electromagnetic chuck,
In the second grinding step after the first grinding step, the work is returned to a suction state substantially parallel to the fall prevention pin against the grinding load of the grindstone by the suction force of the electromagnetic chuck.
A method of grinding a workpiece characterized by: 2. The method of grinding a work according to claim 1, wherein the shoe supports the vicinity of the suction side of the work from the outer peripheral side. 3. The method of grinding a workpiece according to claim 1, wherein the gap between the workpiece and the fall prevention pin is a very small gap. 4. The method of grinding a workpiece according to claim 1 , wherein said fall prevention pin is made of a non-magnetic material . The work includes a continuous cylindrical portion formed continuously in the circumferential direction at the end on the side of attraction by the electromagnetic chuck, and a discontinuous cylindrical portion formed discontinuously in the circumferential direction other than the continuous cylindrical portion. The method of grinding a workpiece according to any one of claims 1 to 4, characterized in that the cylindrical body has a The outer diameter of the cylindrical workpiece, which is attracted to the end face of the spindle by an electromagnetic chuck and is rotatably supported by a shoe, is ground by a grindstone through a first grinding process and a second grinding process while rotating the workpiece. In a shoe-type centerless grinder with
a fall prevention pin that is rotatably provided integrally with the main shaft and that restricts the fall of the work inserted into the outer periphery ;
In the first grinding step, the workpiece falls down in the gap between the workpiece and the fall prevention pin against the attraction force of the electromagnetic chuck due to the grinding load of the grindstone,
In the second grinding process after the first grinding process, due to the adsorption force of the electromagnetic chuck, the grindstone returns to the adsorption state substantially parallel to the fall prevention pin against the grinding load of the grindstone.
A shoe-type centerless grinding machine characterized by: The shoe supports the vicinity of the adsorption side of the work from the outer circumference,
7. The shoe-type centerless grinder according to claim 6, wherein the fall prevention pin is coaxial with the center of the spindle.

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