JP2001138186A - Centerless grinding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centerless grinding method for preventing foreign matters from being caught between an adjusting wheel and a workpiece for improving machining precision and eliminating instability phenomenon so as to improve production efficiency. SOLUTION: A workpiece W is inserted between a rotary grinding wheel 23, and an adjusting wheel 25 disposed to be inclined for a specified angle to an axial center of the rotary grinding wheel 23, and this workpiece W is supported by a workpiece rest 27 while it is rotated roughly at the same circumferential speed as the adjusting wheel 25 to be ground at an outer circumference in this centerless grinding method, where grinding is performed while a part 33 of the adjusting wheel 25 positioned below the workpiece W is washed. As a washing means 31 for that, high pressure cleaning liquid injecting nozzles 35a, 35b for injecting high pressure cleaning liquid and/or a brush 37 to slide and get in contact with the part 33 of the adjusting wheel 25 positioned below the workpiece W for eliminating foreign matter are usable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a centerless grinding method for placing a cylindrical or conical workpiece between a grinding wheel and an adjusting wheel and grinding the outer periphery of the workpiece.

[0002]

2. Description of the Related Art In centerless grinding, a workpiece is inserted between a rotary grindstone and an adjustment wheel, and the outer periphery of the workpiece is ground while being supported by a work rest. The workpiece rotates at substantially the same peripheral speed as the adjusting wheel. The adjusting wheel is inclined several degrees with respect to the axis of the rotating grindstone, and generates a force for pressing or sending the workpiece in one direction. The adjusting wheel is formed into a special shape having a conical shape so that the outer periphery of the workpiece and the outer periphery of the adjusting wheel are brought into contact over the entire length of the workpiece.

The centerless grinding of the cylindrical workpiece W shown in FIG. 7 is performed by holding the workpiece W with the adjusting wheel 1 and the work rest 3 and grinding the workpiece W with the rotary grindstone 5. The workpiece W is rotated at substantially the same speed as the adjusting wheel 1 by the grinding resistance, and the rotating shaft of the adjusting wheel 1 is also tilted so that the front side (the surface side of the paper surface in FIG. 7) is upward. so,
Grinding (through feed grinding) is performed by continuously feeding the workpiece W in the axial direction. At this time, the grinding fluid 8 is supplied to the workpiece W from the grinding fluid nozzle 7 provided above the workpiece W.

In the centerless grinding of the conical workpiece W shown in FIGS. 8 and 9, a screw-shaped groove 9 is provided on the outer periphery of the adjusting wheel 1 made of metal. The workpiece W is fed in the axial direction of the adjusting wheel 1 by the groove 9 shifted in the direction to perform grinding (through feed grinding).

In the through-feed grinding, the workpiece W having a length equal to or more than the width of the rotary grindstone 5 can be continuously processed, so that the outer diameter of a long bar can be ground. On the other hand, in the in-feed grinding, it is possible to form the stepped workpiece W in an overall shape.

[0006]

However, in the above-mentioned conventional centerless grinding method, the abrasive grains and grinding debris (curl-shaped) mixed in the grinding fluid are caught on the adjusting wheel and the work rest, and the workpiece is processed. It enters the contact surface with the object and deteriorates the processing accuracy. Here, the workpiece and the work rest are mainly “slip” and easily eject foreign matter, so that the processing accuracy (roundness, cylindricity) is little affected. Mainly "rolling", the foreign matter is easily bitten, and the bite position of the foreign material is a contact point on the opposite side of the rotary grindstone, so that the processing accuracy is further deteriorated. As a countermeasure, for example, it is conceivable to remove foreign matter from the grinding fluid before supply by passing it through a filter. However, foreign matter that has actually occurred in the grinding unit (crushed abrasive particles, falling off, grinding debris, etc.) is removed on the spot. In particular, foreign matters during grinding wheel dressing and adjustment wheel truing fall down to the whole, so that it is difficult to remove them and a sufficient effect cannot be expected.

In grinding a conical workpiece using a metal adjusting wheel shown in FIGS. 8 and 9, since the adjusting wheel is made of metal, the coefficient of friction is small. The workpiece is rotated, and the workpiece is ground while causing a difference between the peripheral speed of the rotating grindstone and the workpiece.However, if there is a bite of foreign matter between the adjusting wheel and the workpiece, the rotating grindstone is rotated. The rotation determines the peripheral speed of the workpiece. Accordingly, the workpiece is rotated by the rotating grindstone, and the peripheral speed of the workpiece approaches the peripheral velocity of the rotating grindstone,
A so-called crushing state, which is much higher than the peripheral speed of the adjusting wheel, causes an unstable phenomenon such as a touch of the tail of the workpiece. That is, as shown in FIG. 10, the contact state between the adjusting wheel 1, the rotary grindstone 5, and the workpiece W is “rolling” along a cross-sectional line AA at the center in the width direction of the workpiece, and all others are “rolling”. Slip. " As shown in the figure, on the large diameter side of the tapered roller, the peripheral speed of the tapered roller is larger than the adjusted vehicle peripheral speed, and on the small diameter side, the peripheral speed of the tapered roller is smaller than the adjusted vehicle peripheral speed, and the direction of the friction force from the adjusted wheel acting on the tapered roller is obtained. Are opposite to each other with respect to the direction perpendicular to the rotation axis XX, and act in a direction to raise the small diameter side of the tapered roller. Therefore, X
-The X axis tends to tilt and become unstable. When foreign matter enters between the adjusting wheel 1 and the workpiece W, the workpiece W "slips" with respect to the adjusting wheel 1 and the outer peripheral speed of the workpiece W becomes the peripheral speed of the rotary grindstone 5. It tends to approach. This is also confirmed by the fact that a crushing trace is seen on the rotary grindstone 5 by the width of the workpiece W. When the through feed state changes due to such foreign matter biting, as shown in FIG.
The relative speed with respect to the adjustment wheel 1 increases from ΔV (= vt) to ΔV ′, and the original feed speed (vt) of the through feed feed
The axial clearance δt [(groove width of the adjustment wheel)-
(Total length of workpiece)] = 0, which may cause damage to the rotary grindstone, the adjusting wheel, and the workpiece, making the grinding unstable and making it difficult to increase the production efficiency.
In FIG. 8, VR represents the peripheral speed of the adjusting wheel 1, VW represents the peripheral speed of the workpiece W, and α represents the cone angle.

The present invention has been made in view of the above circumstances, and provides a centerless grinding method for preventing foreign matter from being caught between an adjustment wheel and a workpiece, thereby improving the processing accuracy and improving the stability. An object is to improve production efficiency by eliminating the phenomenon.

[0009]

According to the present invention, there is provided a centerless grinding method comprising: a rotating wheel; and an adjusting wheel disposed at a predetermined angle with respect to the axis of the rotating wheel. A centerless grinding method for inserting a workpiece, rotating the workpiece at substantially the same peripheral speed as the adjustment wheel while supporting the workpiece by a work rest, and grinding the outer periphery of the workpiece, It is characterized in that the lower part is ground while being cleaned.

In this centerless grinding method, grinding is performed while the portion of the adjusting wheel located below the workpiece is cleaned, and in particular, the adjusting point, which is a contact point on the opposite side to the rotary grindstone, greatly affects processing accuracy. Foreign matter (crushed abrasive grains, falling off, grinding chips, etc.) generated in the grinding section between the wheel and the workpiece is not re-engaged by the rotation of the adjusting wheel. Thereby, high roundness can be obtained, and the processing accuracy of centerless grinding is improved.

In the centerless grinding method, a thread-shaped groove is provided on the outer periphery of an adjusting wheel made of metal, and the adjusting wheel is arranged at a predetermined angle with respect to the axis of the rotating grindstone. A centerless grinding method in which a conical workpiece is inserted between a groove of a wheel and the outer circumference of the workpiece is rotated while rotating at substantially the same peripheral speed as the adjusting wheel while supporting the workpiece with a work rest. , Wherein high-pressure fluid is jetted from the side opposite to the work rest to the small-diameter portion of the workpiece to perform grinding while holding the small-diameter portion of the workpiece from rising from the work rest. You may.

In this centerless grinding method, the floating of the small outer diameter portion of the conical workpiece is suppressed by the high-pressure fluid injected from the side opposite to the work rest to the small diameter portion of the workpiece, and the workpiece is removed. Excessive grinding of the rotary grindstone and the workpiece due to abnormal advance to the groove gap of the adjustment wheel on the downstream side in the feed direction is avoided, stable grinding is enabled, and production efficiency is increased.

Further, a centerless grinding machine for achieving the above object is provided with a work piece inserted between a rotary grindstone and an adjusting wheel arranged at a predetermined angle with respect to the axis of the rotary grindstone,
A portion of the centerless grinding machine that grinds the outer periphery of the workpiece while rotating the workpiece at substantially the same peripheral speed as the adjustment wheel while supporting the workpiece with a work rest, the portion of the adjustment wheel located below the workpiece; Cleaning means for removing foreign matter that adheres to the adjustment wheel by cleaning and tries to enter between the adjustment wheel and the workpiece from the rotation direction upstream side of the adjustment wheel with respect to the workpiece, It can be characterized by being arranged between the work rest and the adjustment wheel.

In this centerless grinding machine, grinding is performed while the portion of the adjustment wheel located below the workpiece is cleaned by the cleaning means disposed between the work rest and the adjustment wheel. Foreign matter generated in the grinding section between the adjustment wheel, which is the contact point on the opposite side of the rotary grindstone and the workpiece, which greatly affects the accuracy, is no longer caught by the rotation of the adjustment wheel, and high processing is achieved. Centerless grinding with high accuracy becomes possible.

In the centerless grinding machine, the cleaning means may include a high-pressure cleaning liquid injection nozzle for injecting a high-pressure cleaning liquid to a portion of the adjusting wheel located below the workpiece, or a high-pressure cleaning liquid injection nozzle provided below the adjusting wheel. The brush may be a brush that slides on a portion to be located and removes foreign matter adhering to the adjustment wheel, or both the high-pressure cleaning liquid spray nozzle and the brush.

In this centerless grinding machine, when the cleaning means is a high-pressure cleaning liquid injection nozzle, the cleaning liquid injected from the high-pressure cleaning liquid injection nozzle is sprayed at a high pressure on a portion of the regulating wheel located below the workpiece, Foreign matter immediately upstream of the adjustment wheel in the adjustment wheel rotation direction, which is attached to the adjustment wheel and is likely to be caught between the workpiece and the adjustment wheel, is blown off and removed. When the cleaning means is a brush, the brush comes into sliding contact with a portion of the adjustment wheel located below the workpiece, adheres to the adjustment wheel and is bitten between the workpiece and the adjustment wheel. The foreign matter immediately before on the upstream side in the adjustment wheel rotation direction to be adjusted is swept and removed. If the high-pressure cleaning liquid injection nozzle and the brush are used at the same time, the foreign matter removing action can be obtained in an overlapping manner, and it becomes more reliable.

In the centerless grinding machine, a screw-shaped groove is provided on the outer periphery of an adjusting wheel made of metal, and the adjusting wheel is arranged at a predetermined angle with respect to the axis of the rotating grindstone. A centerless grinding machine for placing a conical workpiece between a groove of a car and grinding the outer periphery of the workpiece while rotating the workpiece at substantially the same peripheral speed as the adjusting wheel while supporting the workpiece with a work rest. In the above, the polymer material containing abrasive grains may be slightly protruded from the bottom surface of the groove, and may be embedded so that the surface is parallel to the bottom surface of the groove, at the center of the bottom surface of the groove in the width direction of the groove. .

In this centerless grinding machine, the polymer material containing abrasive grains protruding from the groove bottom of the metal adjusting wheel comes into contact with the workpiece, and the pressure is generated by the elasticity of the polymer material and the spike effect by the abrasive grains is used. The apparent friction coefficient of the metal adjustment wheel increases, making it difficult for the peripheral speed of the conical workpiece to approach the peripheral speed of the rotating grindstone. In addition, stable grinding becomes possible and production efficiency is improved.

In the centerless grinding machine, a screw-shaped groove is provided on the outer periphery of an adjusting wheel made of metal, and the adjusting wheel is arranged at a predetermined angle with respect to the axis of the rotating grindstone. A centerless grinding machine for placing a conical workpiece between a groove of a car and grinding the outer periphery of the workpiece while rotating the workpiece at substantially the same peripheral speed as the adjusting wheel while supporting the workpiece with a work rest. In the high-pressure fluid ejecting means for injecting a high-pressure fluid to the workpiece small-diameter portion to suppress the workpiece small-diameter portion from rising from the work rest,
The work rest may be arranged on the opposite side of the work rest with the workpiece interposed therebetween.

In this centerless grinding machine, when high-pressure fluid is ejected from high-pressure fluid ejection means provided on the opposite side of the work rest with respect to the workpiece, the high-pressure fluid presses the small-diameter portion of the workpiece. The small diameter portion of the workpiece is pressed against the work rest, the lifting of the small outer diameter portion of the workpiece from the work rest is prevented, and the workpiece may abnormally advance to the groove gap of the adjustment wheel on the downstream side in the feed direction. Is prevented.

In the centerless grinding machine, a screw-shaped groove is provided on the outer periphery of an adjusting wheel made of metal, and the adjusting wheel is arranged at a predetermined angle with respect to the axis of the rotating grindstone. A centerless grinding machine for placing a conical workpiece between a groove of a car and grinding the outer periphery of the workpiece while rotating the workpiece at substantially the same peripheral speed as the adjusting wheel while supporting the workpiece with a work rest. In the above, a pressing roller that presses the small diameter portion of the workpiece and suppresses the floating of the small diameter portion of the workpiece from the work rest is disposed on the opposite side of the work rest across the workpiece. It may be a feature.

In this centerless grinding machine, a pressing roller arranged on the opposite side of the work rest with respect to the workpiece presses the small diameter portion of the workpiece, so that the small diameter portion of the workpiece rises from the work rest. And the workpiece is prevented from abnormally advancing to the groove gap of the adjustment wheel on the downstream side in the feed direction.

In the centerless grinding machine, a screw-shaped groove is provided on the outer periphery of an adjusting wheel made of metal, and the adjusting wheel is arranged at a predetermined angle with respect to the axis of the rotating grindstone. A centerless grinding machine for placing a conical workpiece between a groove of a car and grinding the outer periphery of the workpiece while rotating the workpiece at substantially the same peripheral speed as the adjusting wheel while supporting the workpiece with a work rest. , The upstream side of the through-feed angle of the adjustment wheel rotating shaft in the workpiece feed direction may be lower than the downstream side of the workpiece feed direction.

In this centerless grinding machine, the center of the grinding wheel is increased at the entrance of the grinding section (the center of the grinding wheel is lowered) by lowering the downstream side of the adjusting wheel rotating shaft in the direction of workpiece feed, and the center of the grinding wheel is lowered at the exit of the grinding section. The height becomes small (the center height of the adjusting wheel is increased), and even if the small diameter portion of the workpiece slightly rises, the inclination angle is always ensured with respect to the axis of the adjusting wheel and the rotating grindstone. As a result, the generation of a component force in the feed direction is prevented, and the unstable phenomenon does not occur, the rotation speed of the adjusting wheel is increased, and highly efficient and stable grinding can be performed.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a centerless grinding method according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view of a main part of a centerless grinding machine for performing a centerless grinding method according to the present invention. In the following embodiments, the same members will be denoted by the same reference characters, without redundant description.

A rotary grindstone 23 is provided at a grinding portion of the centerless grinding machine 21. The rotary grindstone 23 is rotated by a rotary drive mechanism (not shown) to grind the outer peripheral surface of the workpiece W at the outer periphery. An adjusting wheel 25 is disposed near the rotating grindstone 23 at a predetermined angle with respect to the axis of the rotating grindstone 23, and the adjusting wheel 25 is rotated at substantially the same peripheral speed as the workpiece W. A workrest 27 is disposed in the gap between the rotary grindstone 23 and the adjustment wheel 25 from below in FIG. 1, and the workrest 27 supports the workpiece W at the upper end. A grinding fluid nozzle 29 is provided between the rotary grindstone 23 and the adjustment wheel 25 with a gap between the work rest 27 and the grinding wheel.
Are disposed downward, and the grinding fluid nozzle 29 discharges the grinding fluid from the nozzle portion opened at the lower end toward the work rest 27.

Centerless grinding machine 2 constructed as described above
In the grinding section 1, between the grinding wheel 23 and the adjustment wheel 25,
A cylindrical workpiece W is fed. The workpiece W sent between the rotating grindstone 23 and the adjustment wheel 25 is adjusted by the adjustment wheel 2
5 and the work rest 27, the rotating grindstone 2
By grinding the outer periphery at 3, the wheel is rotated at substantially the same speed as the adjustment wheel 25 due to the grinding resistance. In addition, since the rotating shaft of the adjusting wheel 25 is inclined upward on the front side (the surface side in FIG. 1), the workpiece W is continuously fed in the axial direction and ground (through feed). Grinding) is performed.

By the way, in the centerless grinding machine 21 according to the present embodiment, the cleaning means 31 is disposed between the work rest 27 and the adjustment wheel 25, and the cleaning means 31 is located below the workpiece of the adjustment wheel 25. The part 33 is to be cleaned. The cleaning unit 31 according to this embodiment includes a first high-pressure cleaning liquid injection nozzle 35a, a second high-pressure cleaning liquid injection nozzle 35b, and a brush 37.

The first high-pressure cleaning liquid injection nozzle 35a is provided in the cleaning liquid supply pipe 39, and injects the cleaning liquid so that the workpiece W and the adjustment wheel are rotated from the rotation direction upstream side of the adjustment wheel 25 with respect to the workpiece W. 25, the cleaning is performed up to the rolling portion, and adheres to the adjusting wheel 25 to attach the adjusting wheel 25 and the workpiece W.
The foreign matter which tries to enter between them is removed.

The brush 37 has a base end at the cleaning means main body 31a.
The tip is slidably contacted with a portion 33 of the adjusting wheel 25 located below the workpiece, and adheres to the adjusting wheel 25 so as to be caught between the workpiece W and the adjusting wheel 25. The foreign matter on the upstream side in the rotation direction of the adjustment wheel is removed by sweeping.

The second high-pressure cleaning liquid injection nozzle 35b is provided in the cleaning liquid supply pipe 39 similarly to the above-described first high-pressure cleaning liquid injection nozzle 35a. The cleaning liquid is sprayed toward the sliding contact portion with the brush 37 to cooperate with the sliding contact of the brush 37 to adhere to the adjusting wheel 25 and to enter between the adjusting wheel 25 and the workpiece W. Is removed.

As the material of the brush 37, alloys such as nickel, cobalt, and chromium, ceramic fibers and the like can be suitably used, and stainless steel fibers and carbon fibers are also applicable. Material selection is creep characteristics, friction and
It takes into account the wear characteristics and rust resistance. The brush 37 is
The base end of a thin fibrous body made of such a material is provided so as to be exchangeably sandwiched between the cleaning means main body 31a using, for example, a backing plate 41 or the like.

The cleaning liquid filters the grinding liquid as finely as possible and sprays it at a high pressure. As a measure of the degree of cleaning by filtering, it is desirable that abrasive particles and grinding debris of 0.1 μm or more can be removed. In addition, it is desirable that the injection pressure of the cleaning liquid is 30 to 50 kg / cm ² .

The cleaning means 31 can be configured to move, for example, in synchronization with the movement of the workpiece W in the feed direction. In this case, a guide rail or the like (not shown) extending in the axial direction of the adjustment wheel 25 is provided in the gap between the work rest 27 and the adjustment wheel 25, and the cleaning means main body 31a is slidably provided on the guide rail. The movement synchronized with the feed of the workpiece W becomes possible. Further, the cleaning means 31 includes:
It is preferable to provide a plurality of the adjusting wheels 25 in the axial direction. Thereby, a plurality of workpieces W to be continuously processed
Can be washed at the same time.

The cleaning means 31 includes a first high-pressure cleaning liquid injection nozzle 35a and a second high-pressure cleaning liquid injection nozzle 35a.
Only one of the b and the brush 37 may be provided. That is, it is only necessary that the foreign matter adhering to the adjustment wheel 25 and entering between the adjustment wheel 25 and the workpiece W can be efficiently removed. In the cleaning means 31 according to the present embodiment, by making these act redundantly,
This makes it possible to reliably remove foreign matter.

In the centerless grinding method using the centerless grinding machine 21, the portion 33 of the adjusting wheel 25 located below the workpiece is cleaned while being cleaned by the cleaning means 31, and this greatly affects the processing precision. The adjustment wheel 25 and the workpiece W, which are the contact points on the opposite side of the rotating grindstone 23,
In the meantime, foreign matter that has actually occurred in the grinding section (crushing of abrasive grains, falling off,
Grinding debris, etc.) does not bite into the grinding portion again due to the rotation of the adjusting wheel 25. Thereby, high roundness can be obtained, and the processing accuracy of centerless grinding is improved.

It is known that abrasive particles have the most adverse effect on the acoustic problem of HDD bearings. Also in the case of the centerless grinding according to the present embodiment, this abrasive-based foreign matter not only generates scratches (scratches),
It is thought that it has also adversely affected grinding accuracy,
By constantly cleaning the rotating grindstone 23, these problems are eliminated, and it can be sufficiently expected that the processing accuracy is improved.

The present embodiment is mainly intended for centerless through-feed grinding of a cylindrical workpiece W for a machine tool. It is also effective for centerless infeed grinding of objects.

Next, a centerless grinding machine according to a second embodiment for centerless grinding a conical workpiece will be described. FIG. 2 is a schematic view of a main part of a centerless grinding machine according to a second embodiment of the present invention.

A rotary grindstone 53 is provided at a grinding portion of the centerless grinder 51, and the rotary grindstone 53 is rotated by a rotation drive mechanism (not shown) to grind the outer peripheral surface of the workpiece W at the outer periphery. An adjusting wheel 55 is disposed near the rotating grindstone 53 at a predetermined angle with respect to the axis of the rotating grindstone 53, and the adjusting wheel 55 is rotated at substantially the same peripheral speed as the workpiece W. A work rest (not shown) is provided in the gap between the rotary grindstone 53 and the adjustment wheel 55 on the back side of the paper surface of FIG. 2, and the work rest supports the workpiece W at the upper end. Rotating wheel 53 and adjustment wheel 5
2, a grinding fluid nozzle (not shown) is arranged downward from above in FIG. 2 with a gap from the work rest, and the grinding fluid nozzle is ground from the nozzle portion opened at the lower end toward the work rest. The liquid is discharged.

The adjusting wheel 55 is made of metal, and has a thread-shaped groove 57 formed on the outer periphery. Centerless grinder 51
Then, the conical workpiece W is inserted between the rotating grindstone 53 and the groove 57 of the adjusting wheel 55, and the workpiece W is rotated at substantially the same peripheral speed as the adjusting wheel 55 while supporting the workpiece W on the work rest. Infeed grinding is performed on the outer periphery of the workpiece W.

The groove 57 formed in the adjusting wheel 55
In the groove bottom surface 59, a polymer material 61 containing abrasive grains is embedded in the center portion in the groove width direction so as to protrude slightly from the groove bottom surface 59 and to have a surface parallel to the groove bottom surface 59.

More specifically, the polymer material 61 containing abrasive grains
Is composed of, for example, abrasive grains (ceramics) such as SiC and Al ₂ O ₃ and a polymer material having elasticity. The abrasive-containing polymer material 61 is disposed at the center of the adjusting wheel 55 in the axial direction with respect to the length L of the workpiece W (for example, l / L).
= 1/2), affixed at a depth a, and grind the groove 57 in this state.

Slight protrusion δ of polymer material 61 containing abrasive grains
Is the preload during use (the elastic modulus is smaller than steel).
Further, a concave portion 63 for embedding the polymer material 61 containing abrasive grains.
Is inclined toward the flange 65 side of the groove 57 by the β angle. Groove 57
In addition, it is to secure the allowance in consideration of the modification (broken line) of the flange 65 surface. Then, the workpiece W and the adjusting wheel 55
The overall coefficient of friction with l / L
And δ are determined by appropriately setting dimensions.

In this centerless grinding machine 51, the polymer W containing abrasive grains is provided at the center of the groove bottom surface 59 of the adjusting wheel 55 made of metal, so that the workpiece W is 61, the apparent friction coefficient increases due to the pressure generated by the elasticity of the polymer material and the spike effect of the abrasive grains. This makes it difficult for the peripheral speed of the conical workpiece W to approach the peripheral speed of the rotary grindstone 53,
Excessive increase in the peripheral speed due to the rotary grindstone 53 does not occur in the workpiece W, stable grinding can be performed, and production efficiency increases.

Next, a centerless grinding machine according to a third embodiment for centerless grinding a conical workpiece will be described. FIG. 3 is a perspective view of a main part of a centerless grinding machine according to a third embodiment of the present invention, and FIG. 4 is a front view of the main part seen from the direction of the adjustment axle axis of FIG.

The centerless grinding machine 71 is provided with
A high-pressure fluid injection unit 73 is provided between the control wheel 3 and the adjustment wheel 55. The high-pressure fluid ejection means 73 is arranged on the opposite side of the work rest 27 with the workpiece W interposed therebetween. A plurality of slits 77 are opened in the casing 75 of the high-pressure fluid ejecting means 73 in correspondence with each of the plurality of workpieces W to be fed in the feed direction, and the high-pressure fluid injected from the slits 77 has a small diameter of the workpiece W. Part. Therefore, the workpiece W hit by the high-pressure fluid is prevented from rising from the work rest 27 at the small diameter portion.

More specifically, the casing 75 is provided with a screw-shaped rotary valve 79, and this rotary valve 79 is
By rotating in synchronism with the rotation of 5, the opening of the slit 77 is restricted and opened only by the length s of the small-diameter portion, so that the high-pressure fluid is always supplied in accordance with the feed direction of the workpiece W. It has become.

At this time, the pressing force f of the workpiece W is given by f = bs · PS, where the supply pressure PS and the slit width b are given, and this force is used as the pressing force against the work rest 27. It will be added to the small diameter portion of the object W. The pressing force f is, for example, b = 2 mm, s = 3 mm, PS = 3
If it is 0 kg / cm ² , it will be 1.8 kg.

Here, the supply pressure PS is 70 kg / cm ²
Until it is possible. The rotation of the rotary valve 79 may be performed by a synchronous motor, or may be performed by gear adjustment from the adjusting wheel 55. It is considered that gear reduction can be easily performed by using a two-stage system.

In the centerless grinding machine 71, when high-pressure fluid is jetted from high-pressure fluid jetting means 73 provided on the opposite side of the work rest 27 with the work W interposed therebetween, the high-pressure fluid is jetted from the work W Will be pressed. As a result, the small-diameter portion of the workpiece W is pressed against the work rest 27, the lifting of the small-diameter portion from the work rest 27 is prevented, and the workpiece W abnormally advances to the groove gap of the adjustment wheel 55 on the downstream side in the feed direction. Is prevented.

Next, a centerless grinding machine according to a fourth embodiment for centerless grinding a conical workpiece will be described. FIG. 5 is a perspective view of a main part of a centerless grinding machine according to a fourth embodiment of the present invention, and FIG. 6 is a front view of the main part seen from the direction of the adjustment axle axis of FIG.

The centerless grinder 81 is provided with a rotating grindstone 5.
The pressing roller 83 is provided between the adjusting wheel 3 and the adjusting wheel 55. The pressing roller 83 is arranged on the opposite side of the work rest 27 with the workpiece W interposed therebetween. A threaded elastic body 85 is wound around the outer periphery of the pressing roller 83, and the pitch of the elastic body 85 is set to be equal to the small diameter portion of the workpiece W arranged in the feed direction. The elastic body 85 is formed of, for example, rubber or resin. The pressing roller 83 presses the small-diameter portion of the workpiece W through the elastic body 85, thereby preventing the small-diameter portion from rising from the work rest 27. Also,
Since the pressing roller 83 has a small diameter, it is preferable that the backup roller 86 assists the rigidity.

In the grinding of a bearing ring by a centerless grinding machine, a method of pressing a ring, which is an elastic body, with a ring holder similar to a top blade (upper work rest) is used in order to improve falling accuracy (however, At the top of the ring). The present embodiment is a method in which a solid workpiece W is pressed by an elastic body in the opposite manner. In this case, the workpiece W
Since the peripheral speed difference between the pressure roller 83 and the pressing roller 83 is almost close to the peripheral speed of the adjusting wheel 55, it is important to select a material that is resistant to sliding wear as the material of the pressing roller 83 and the elastic body 85 (for example, carbon fiber or glass). Fiber).

The centers of the workpiece W, the pressing roller 83 and the backup roller 86 are arranged on a straight line.
Accordingly, the pressing roller 83 rotates synchronously with the adjustment wheel 55, and the backup roller 86 rotates at the same speed as the pressing roller 83.

In the centerless grinding machine 81, the pressing roller 83 disposed on the opposite side of the work rest 27 with respect to the workpiece W presses the small diameter portion of the workpiece, so that the work of the small diameter portion of the workpiece is pressed. Floating from the rest 27 is prevented, and the workpiece W is prevented from abnormally advancing to the groove gap of the adjustment wheel 55 on the downstream side in the feed direction.

Further, in the centerless grinding machines of the above-described embodiments, the through-feed angle of the adjusting wheel of the adjusting wheel has conventionally been increased (the center height is decreased).
Conversely, a set that lowers the front side invites a better effect in preventing the workpiece W from rising.
That is, the upstream side of the through-feed angle of the adjusting wheel rotating shaft in the workpiece feeding direction is lower than the downstream side of the workpiece feeding direction.

As described above, the downstream of the adjusting wheel rotating shaft in the workpiece feeding direction is lowered, so that the center height becomes large at the entrance of the grinding section (the center height of the adjusting wheel is lowered), and the center height is obtained at the grinding section exit. Becomes smaller (the height of the adjustment car rises). Even if the small-diameter portion of the workpiece W rises slightly, the inclination angle is always secured with respect to the axis of the adjusting wheel and the rotating grindstone, thereby preventing the generation of a component force in the feed direction and causing unstableness. The phenomenon does not occur, the number of rotations of the adjusting wheel is increased, and highly efficient and stable grinding can be performed. However, considering the contact point between the head and the adjustment wheel, it is necessary to take measures against head chamfer accuracy, chamfer scratches, and the like. Such means are considered to be effective for rough processes where (unstable grinding) jars are particularly problematic. Considering these comprehensively, the peripheral speed angle of the workpiece W can be appropriately adjusted by adjusting the center height of the adjusting wheel.

[0059]

As described above in detail, the centerless grinding method according to the present invention grinds while cleaning the portion of the adjustment wheel located below the workpiece, which greatly affects the machining precision. Therefore, it is possible to reliably prevent foreign matter generated in the grinding portion from being re-engaged by the rotation of the adjustment wheel between the adjustment wheel, which is a contact point on the opposite side of the rotating wheel, and the workpiece. Roundness can be obtained. As a result, the processing accuracy of centerless grinding can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a centerless grinding machine for performing a centerless grinding method according to the present invention.

FIG. 2 is a schematic view of a main part of a centerless grinding machine according to a second embodiment of the present invention.

FIG. 3 is a perspective view of a main part of a centerless grinding machine according to a third embodiment of the present invention.

FIG. 4 is a front view of a main part as viewed from a direction of an adjustment axle of FIG. 3;

FIG. 5 is a perspective view of a main part of a centerless grinding machine according to a fourth embodiment of the present invention.

FIG. 6 is a front view of a main part as viewed from the adjustment axle axis direction of FIG. 5;

FIG. 7 is a schematic diagram of a main part of a centerless grinding machine that performs a conventional centerless grinding method.

FIG. 8 is a side view of the conventional work piece viewed from a rotary grindstone of a centerless grinding machine for centerless grinding a conical work piece.

9 is a front view of the cone-shaped workpiece of FIG. 8 as viewed from the axial direction of the adjustment wheel.

FIG. 10 is a plan view showing the state of contact between the rotating grindstone, the adjusting wheel, and the conical workpiece, as viewed from a direction perpendicular to the axis of the adjusting wheel.

[Explanation of symbols]

 21, 51, 71, 81 Centerless grinding machine 23, 53 Rotating grindstone 25, 55 Adjustment wheel 27 Work rest 31 Cleaning means 33 Part of adjustment wheel located below workpiece 35a, 35b High-pressure cleaning liquid injection nozzle 37 Brush 57 Groove 59 Groove bottom surface 61 Polymer material containing abrasive grains 73 High-pressure fluid jetting means 83 Pressing roller W Workpiece

Claims (1)

[Claims] 1. A work piece is inserted between a rotary grindstone and an adjustment wheel arranged at a predetermined angle with respect to an axis of the rotary grindstone, and the adjustment wheel is supported while the work piece is supported by a work rest. A centerless grinding method for grinding the outer periphery of the workpiece while rotating at substantially the same peripheral speed as described above, wherein the grinding is performed while cleaning a portion of the adjusting wheel located below the workpiece. .