JPH07246548A - Grinding method and grinding device of minute stepped shaft - Google Patents

Abstract

PURPOSE:To prevent the mixing of a chuck error by rotating the base shaft of a minute stepped shaft by a friction transmission while supporting it with a regulating grinding wheel form member and a blade, so as to grind with a grinding wheel, and moving the minute stepped shaft being ground to the grinding wheel side at a specific speed, as well as contacting a buckup shoe to the minute shaft part of the minute stepped shaft. CONSTITUTION:The large diameter part of a minute stepped shaft 8 is supported by a blade 1 similar to the blade of a centerless grinder, and a regulating grinding wheel form member 9, and it is rotated by a friction transmission. And both members 1 and 9 are approached to a grinding wheel 4 at the relative speed V while maintaining the blade 1 and the regulating grinding wheel form member 9 as it is, and the minute shaft part of the minute stepped shaft 8 is ground by the grinding wheel 4. At the same time, a backup lever 16 is fed to the side of the grinding wheel 4, and abutted to a minute regulating stopper 18. As a result, the backup lever 16 is rotated in the direction r4, a backup shoe 16a is moved in the direction a at the speed 2V, and it is pressed to the minute shaft part of the minute stepped shaft 8, so as to back up the minute stepped shaft 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member, such as a microdrill, in which a cylindrical portion having an extra fine dimension and a base shaft portion having a relatively larger diameter than that are concentrically integrally connected. The present invention relates to a method and a device for grinding a columnar portion having the above-mentioned extra-fine dimension (hereinafter referred to as an extra-fine stepped shaft). In the present invention, the term “cylindrical” means not only a true geometrical solid cylinder, but also a cone with a small vertical angle (so-called taper axis).
Is meant to include. Further, the ultrafine shaft means a shaft having a diameter of 1 mm or less in terms of a grinding finish dimension.

[0002]

2. Description of the Related Art Centerless grinding is known as a technique for precisely grinding a cylindrical member. FIG. 5 shows a conventional example of a centerless grinder, (A) is an explanatory view in which dimension symbols and motion symbols are entered in a schematically drawn front view, and (B) is a main part of a centerless grinder for stepped shaft machining. It is the figure which added the to-be-processed object to the exploded plan view of FIG. The top surface of the vertical plate-shaped blade 1 is an inclined surface 1a. The adjusting grindstone 2 is a rotating grindstone having a horizontal rotation axis (vertical to the paper surface), and the cylindrical work piece 3 is supported by the blade 1 and the adjusting grindstone 2. The adjusting grindstone 2 rotates in the direction of arrow r ₁ , and the work piece 3 is rotated in the direction of arrow r ₂ . The above adjusting whetstone is composed of, for example, synthetic rubber in which abrasive grains are kneaded,
It is a member that also has a grinding function. The grindstone 4 is a rotary grindstone having a horizontal axis of rotation (vertical to the plane of the paper), and is rotated in the direction of the arrow r ₃ at a peripheral speed higher than that of the workpiece 3 to come into contact with the workpiece 3. To grind. Since the work piece 3 to be ground is supported and rotates instinctively as described above, it is machined into a highly accurate perfect circle. The centerless grinding machine has a function of creating a perfect circle in this way (circle forming function). With the above centerless grinding machine,
For example, in the case of centerless grinding of the outer peripheral surface of a stepped workpiece as shown in FIG. 5B, the adjustment grindstone 6 having a stepped cylindrical surface and the stepped cylindrical surface as shown in FIG. The stepped grinding wheel 7 is used. This FIG. 5 (B) is drawn as an exploded view and the illustration of the blade is omitted so that the relationship between the stepped workpiece and the stepped adjustment grindstone and the stepped grinding wheel can be easily understood. However, in use, it is shown in FIG.
In the same manner as in (A), while the stepped workpiece 5 is supported and rotated by the stepped adjustment grindstone 6 and the blade, the stepped grinding wheel 7 grinds the large diameter portion and the subtotal portion. Figure 5
The dimension H shown in (A) is the core height. Centerless grinding can be carried out smoothly and with high accuracy by optimizing the center height.

[0003]

The stepped workpiece 5 shown in FIG. 5B is, for example, a material for a drill, and the large diameter portion (the portion corresponding to the shank) has a thickness in centimeters. If the diameter of the small-diameter portion (the portion corresponding to the cutting edge) is in millimeters, the centerless grinding process can be performed without difficulty. However, as in the case of the material for a drill shown in FIG. 6, if the thin shaft diameter is 1 mm or less, grinding is technically difficult,
Especially when it is 0.3 mm or less, it is very difficult to satisfy the required accuracy of the work piece. Furthermore, in the case of a relatively brittle material (for example, a super hard material), it is even more difficult because the ultrafine shaft portion may be broken. In the present invention, the term “cylindrical” is not limited to a cylinder in a strict sense in terms of three-dimensional geometry, but includes a cone having a small apex angle (that is, a tapered axis).
A member in which a cylindrical portion larger than the ultrafine shaft and the ultrafine shaft are concentrically aligned and integrally connected is referred to as an ultrafine stepped shaft.

In the prior art, the extra fine stepped shaft is not suitable for centerless grinding, and a method of using a cylindrical grinder to chuck a large diameter portion and grind the extra fine shaft portion has been used. When such a method is adopted, a. Concentricity error may occur due to chuck error. b. The grinding finish accuracy is affected by the spindle rotation accuracy. c. Since it does not receive the ultrafine shaft part that is the grinding part, it cannot perform efficient grinding (if you try to increase the efficiency, the ultrafine shaft part will break). d. It is difficult to finish with high precision because it does not receive the ultra-fine shaft that is the grinding part. There is such a problem. Focusing on the fact that the problems a to d are related to the support and rotary drive of the workpiece, it is possible to apply the method of supporting and rotary drive of the workpiece by the centerless grinding technique. It cannot be realized because there is a contradiction related to the basics of the grinding technique as described below. That is, the reduced state of the diameter of the portion to be ground is different. FIG. 7 is a schematic diagram shown for explaining the difference between centerless grinding and cored grinding, and FIG. 7A shows a state in which the base shaft portion of the extra fine stepped shaft is centerless ground (centerless grinding),
(B) shows a state in which the fine shaft portion of the fine stepped shaft is ground by a grinding wheel. However, since it is schematically illustrated, the dimensional relationship does not necessarily have a shape in which the substance is uniformly scaled. (A) When the outer peripheral surface of the base shaft portion 8a is centerless ground as shown in the figure, if the grinding wheel 4 is brought close to the adjustment wheel 2 and the blade 1 by a minute dimension d,
The diameter of the base shaft portion 8a, which is the object to be ground, is reduced by the dimension d. In comparison with this, as shown in FIG.
When grinding the extra-fine shaft portion 8b with the grinding wheel 4 while supporting and rotating the base shaft portion 8a of the above with the adjusting grindstone 2 and the blade 1,
When the grinding wheel 4 is moved closer by a minute dimension d, the radius of the ultrafine shaft portion 8b, which is the object to be ground, is reduced by the dimension d. Reducing the radius by the dimension d means reducing its diameter by 2d. As described above, the diameter of the base shaft portion 8a is reduced by the dimension d and the diameter of the ultrafine shaft portion 8b is reduced by the dimension 2d. Therefore, in the method as shown in FIG. It is not possible to apply the technology related to the support and rotary drive of the object to be ground. The present invention has been made in view of the above circumstances, and when grinding is performed by a method in which the diameter of the workpiece is reduced by a dimension corresponding to twice the movement amount of the grinding wheel, the workpiece is Providing a grinding method and a grinding device that support instinctively to prevent mixing of chuck errors, support the grinding reaction force, and have high accuracy, high efficiency, and good yield (without fear of breakage) The purpose is to grind the ultrafine shaft portion of the ultrafine stepped shaft.

[0005]

The basic principle of the present invention created to achieve the above objects will be briefly described with reference to FIG. In order to receive the cutting of 8b, a backup shoe Bs shown by a virtual line is provided. Then, as the grinding wheel 4 moves relative to the ultrafine shaft portion 8b by the minute dimension d as indicated by the arrow R, the backup shoe is pushed in the direction of the arrow L by the minute dimension d to move the ultrafine shaft portion 8b. The sliding state of the extra-fine shaft portion 8b is kept constant while compensating for the reduction in diameter. As described above, it is preferable to use a lever to push the backup shoe by a predetermined ratio, but it is also possible to automatically drive the backup shoe by applying NC technology. As a concrete method for industrially applying the above-mentioned principle, a method for grinding an ultrafine stepped shaft according to the present invention is a cylindrical ultrafine shaft and a base shaft having a diameter larger than that of the ultrafine stepped shaft that are concentrically and integrally connected. In the method for grinding the extra fine shaft portion of the stepped shaft, the extra fine stepped shaft is formed by a blade similar to or similar to the blade of the centerless grinder and an adjusting grindstone member similar to or similar to the adjusting grindstone of the centerless grinder. While supporting the portion of the large-diameter base shaft and rotating the adjustment grindstone-shaped member to rotate the ultrafine stepped shaft, both of these without changing the relative position of the blade and the adjustment grindstone-shaped member. The member of (1) is brought closer to the rotating grinding wheel at a speed V, and the minute shaft portion of the rotating minute stepped shaft supported by the both members is brought into contact with the grinding wheel. The outer peripheral surface of the ultrafine shaft is ground
In addition, the backup shoe is made to slide against the ultrafine shaft portion ground as described above, and a speed of about 2V is applied in the direction of bringing the backup shoe closer to the grinding wheel.
The feature is that you can move with. In the basic principle described above with reference to FIG. 7B, it has been described that the backup shoe is pushed by the dimension d in the direction of arrow L (direction approaching the grinding wheel 4). If the same thing is considered on the basis of a grinding wheel, the grinding wheel 4 is dimension d in the direction of arrow R (to the right).
Therefore, the backup shoe must move to the left (L direction) by the dimension 2d. Furthermore, in practice, the above movement must be maintained at all moments, so the integrated value of the dimension d
This is treated as a speed V differentiated with respect to time as in the above means. Backup shoe speed 2V as above
The second invention method, which is dependent on the above-mentioned invention method, is a fulcrum that can be moved at a relative speed V with respect to the grinding wheel together with the blade without changing the relative position with respect to the blade. Supports the backup lever near the center so that it can be tilted,
A backup shoe is fixed near one end of the backup lever, and a stopper fixedly installed on the bearing member of the grinding wheel is brought into contact with the other end of the backup lever. Thus, when the ultrafine stepped shaft supported by the blade and the adjusting grindstone member approaches the grinding wheel at the speed V, the backup shoe is made to approach the grinding wheel at a speed of about 2V. In carrying out the method of the invention described above, a v-shaped groove is provided at a position where the backup shoe slides against the extra-fine shaft portion, and the distance from the fulcrum near the central portion of the backup lever to the backup shoe is L ₄ .
Let L _{3 be} the distance from the driven point at which the backup lever contacts the stopper to the fulcrum near the center,
The distance L ₄ is set to be substantially equal to the distance L ₃ , preferably L ₄ is set to be slightly larger than L ₃ , and further preferably the distance L ₄ is set to about 1.1 times the distance L _3. Is desirable. However, the above-mentioned about 1.1 times does not mean 1.100 times, but it is a numerical range that rounds to 1.1 (1.05-
1.14) is meant. In the present invention, the adjusting whetstone-like member may be a member that can be used as an adjusting whetstone for a centerless grinder, or a similar member that is not suitable for use as an adjusting whetstone for a centerless grinder. is there. Each of these has advantages and disadvantages, which will be described in detail in the section of Examples.

The structure of the device created for carrying out the above-mentioned method of the invention will be described with reference to the schematic view of FIG. 3. The base shaft portion (8a) of the extra fine stepped shaft (8) which is the workpiece.
A blade (1) similar to the blade of a centerless grinder, and an adjusting whetstone-like member (9) similar to or similar to the adjusting whetstone of the centerless grinder, and the ultrafine stepped shaft. In addition to a grinding wheel (4) made of a rotary wheel that contacts the shaft (8b) and grinds it, and a backup shoe (16a) that supports the grinding reaction force by sliding on the ultrafine shaft, An interlocking mechanism is provided to allow the backup shoe to approach the extra-fine shaft portion following the reduction in size of the extra-fine shaft portion by grinding, and to keep the sliding contact pressure between the backup shoe and the extra-fine shaft portion substantially constant. In the above-mentioned invention device, the backup shoe is moved in accordance with the reduction due to the grinding of the extra-fine stepped shaft, and the contact pressure between the two is kept substantially constant. Wherein the interlocking mechanism in the second invention apparatus subordinate, the backup shoe (1 to the end of one
6a) is provided for backup, and a pivot shaft for pivotally supporting the backup lever (16) and the vicinity of the central portion of the backup lever as a fulcrum that does not change the relative position of the adjusting grindstone member (9) with respect to the bearing member. 15) and stopper means (18) which is installed so as not to change the relative position of the grinding wheel (4) with respect to the bearing member and comes into contact with the other end of the backup lever. It is characterized by

[0007]

According to the above-mentioned means, the base shaft portion of the extra fine stepped shaft is rotated by frictional transmission while being supported by the adjusting grindstone member and the blade. In this way, since the extra fine stepped shaft is supported by using the cylindrical surface of the outer periphery as a proof, there is no fear that a concentricity error will occur due to a chuck error when attaching a workpiece (extra fine stepped shaft) to the spindle. .
Further, since it is not necessary to provide a center hole in the ultrafine shaft portion for centering, the lower limit of the thickness dimension of the ultrafine shaft portion is not restricted in this sense. Further, as described above, since the work piece is supported innocently, there is no fear of being affected by the rotation accuracy of the spindle chucking the work piece, and high accuracy can be obtained. Moreover, the backup shoe is kept in sliding contact with the extra-fine shaft part that is the grinding part, and the contact pressure is kept constant, so high-efficiency grinding is possible, and even if high-efficiency grinding is performed, the extra-fine shaft part is performed. There is no risk of breakage. Since the backup shoe receives the portion to be ground as described above, the portion to be ground does not escape even when the grinding wheel comes into contact therewith, so that the ultrafine shaft portion can be ground with high accuracy.

If a lever mechanism is used as a means for following the backup shoe at a speed 2V which is twice the moving speed V (cutting speed) of the grinding wheel, accurate control can be performed with a simple structure. It is suitable. The above actions work comprehensively to grind ultra-fine stepped shafts with high precision, high efficiency, high yield, without requiring special skill, without fear of human error, and at low cost. You can

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a schematic front view of one embodiment of the grinding apparatus of the present invention created to carry out the method for grinding an ultrafine stepped shaft according to the present invention, for the sake of easy understanding of the structure and operation. In addition, since the connection relations and relative movements of the respective constituent members are deformed and drawn so as to be clearly expressed, the figures are not necessarily projections of the substantial shape of the apparatus of the embodiment. The extra-fine stepped shaft 8 has a large-diameter base shaft (reference numeral 8a in FIG.
And the adjusting whetstone-shaped member 9. The adjusting grindstone member 9 of the present embodiment is composed of a rubber roller containing no abrasive grains. When the adjusting grindstone-like member 9 is made of such a material, the coefficient of friction of the extremely fine stepped shaft is larger than that of the adjusting whetstone containing abrasive grains. Therefore, the rotational driving force of the extremely fine stepped shaft is large. The shaft portion can be ground with high efficiency. As an example different from this example, if the adjusting grindstone-like member 9 is constituted by a rubber roller in which abrasive grains are kneaded, the adjusting grindstone-like member 9 is used as an adjusting grindstone for centerless grinding, and a base shaft of an extra fine stepped shaft is used. This is convenient because it can also be used for centerless grinding of the portion (reference numeral 8a in FIG. 6). The grinding wheel 4 is rotatably supported by a stationary bearing 11, and is driven by an arrow r ₃ by a driving means (not shown).
It can be rotated in the direction. The stationary bearing 11 is installed on the stationary base 11. On the other hand, the adjusting grindstone-shaped member 9 is the moving bearing 1 installed on the slide base 12.
It is rotatably supported by 3, and is rotated in the direction of arrow r ₁ by a driving means (not shown). The blade 1 is fixedly installed on the slide base 12.
The above-mentioned names of the stationary bearing, the stationary base, the moving bearing, and the slide base are named for convenience of understanding the operation based on the schematic structure of FIG. The approach and separation of the grindstone member and the blade are relative. That is, even if the grinding wheel 4 is moved in the left-right direction in the figure while the adjusting grindstone-shaped member 9 and the blade 1 are kept at the fixed positions, the same action and effect can be obtained. It does not mean absolute stationary / moving with reference to. A stationary arm 17 fixed integrally with the stationary bearing 11,
The name of the moving arm 14 fixed integrally with the moving bearing 13 is also given so as to facilitate understanding of the operation in this figure.

Near the tip of the moving arm 14, a central portion of a backup lever 16 is tiltably attached by a pivot shaft 15. A backup shoe 16a is formed near the lower end of the backup lever 16 so as to be in sliding contact with the extra-fine shaft portion of the extra-fine stepped shaft 8. The shape of the backup shoe will be described later in detail with reference to FIG. Of the constituent members described above with reference to FIG. 3, the planar arrangement relationship of main components is shown in FIG. FIG. 2 is a plan view of the external appearance of the adjusting grindstone member, the blade, the ultrafine stepped shaft, and the grinding wheel extracted from the above embodiment and separated from each other, and the cross-sectional shape of the backup shoe is added and the operation is performed. FIG. 6 is a view additionally including an arrow for explaining and a circular arc arrow indicating a rotation direction. As can be seen from FIG. 2 described above, the base shaft portion 8a of the extra fine stepped shaft 8 is supported by the blade 1 and the adjusting grindstone member 9 and is rotated in the direction of the arc arrow r ₁ . The ultrafine shaft portion 8b of the ultrafine stepped shaft 8 is contacted by the grinding wheel 4 and ground. At this time, the extra-fine shaft portion 8b is backed up so as to be smoothly ground by the sliding contact of the backup shoe 16a, and in particular, the extra-fine shaft portion 8b is prevented from being broken due to excessive bending stress. Since the diameter of the ultrafine shaft portion 8b is reduced by grinding, it is necessary to move the backup shoe 16a in the direction of arrow a to compensate for this. The interlocking mechanism of the backup shoe 16a will be described with reference to FIG. A finely adjustable stopper 18 is installed at the tip of the stationary arm 17 described above (details of the structure will be described later with reference to FIG. 1). When the slide base 12 slides to the left in the figure, the backup lever 1 pivotally supported by the moving arm 14
6 also moves to the left, and the driven portion 16b at the upper end of the backup lever 16 comes into contact with the fine adjustment stopper 18 and is prevented from moving to the left. When the slide base 12 continues to move to the left, the backup lever 16 is rotated clockwise (clockwise) as indicated by the arc arrow r ₄ , and the backup shoe 16a is advanced to the left in the figure. The pivot shaft 15 is a backup shoe 16
It is located approximately in the center between a and the driven part 16b (specifically, it is slightly above the center as will be described later with reference to FIG. 1, but at the present stage where the outline of the operating principle is described, it is approximately in the center. ). Therefore, the slide base 1
When 2 moves to the left by the minute dimension d, the adjusting grindstone member 9 and the blade 1 move to the left by the minute dimension d, and the ultrafine stepped shaft 8 supported by these members moves to the left by the minute dimension d. Then, the ultrafine shaft is ground by the grinding wheel 4 rotating at a fixed position, and the radius thereof is reduced by the minute dimension d (the diameter is reduced by 2d).

With the above operation, the pivot shaft 15 advances to the left by a minute dimension d, but since the driven portion 16b is blocked from advancing, the backup shoe 16a is advanced to the left by about 2d. . In this way, the diameter of the ultrafine shaft is reduced by 2d, and the backup shoe 16a
Moves to the left by a dimension 2d, so that the backup shoe 16a keeps a constant sliding contact with the ultrafine shaft.

In the above description of the operation with reference to FIG. 3, the movement of the minute dimension d within a minute time was described by comparing the states before and after the movement. The operation at a certain moment will be described as follows. (See FIG. 3) When the slide base 12 is moved to the left in the drawing at the speed V, the driven arm 14 is moved to the left in the drawing at the speed V, and the moving portion 16b is prevented from moving forward. Therefore, the backup shoe 16a is advanced to the left in the figure at a speed of about 2 V, and the sliding contact state with the ultrafine shaft is kept constant. The outline of the configuration of the embodiment of the present invention and the outline of the operation thereof have been described above with reference to the schematic diagram shown in FIG. 3. Next, the detailed configuration and operation thereof will be described. FIG. 1 shows an embodiment of a grinding apparatus for a shaft with a stepped shaft according to the present invention, which is configured to carry out a method for grinding a shaft with a stepped shaft according to the present invention. It is explanatory drawing which added the reciprocal arrow which represents operation | movement while adding a dimension symbol and a dimension line. FIG. 4 is a back view of the above embodiment. 1 and 4, constituent members given the same reference numerals as those in FIG. 3 are the same members. In FIG. 3, as a schematic diagram useful for explanation of the structural function, it is drawn by appropriately modifying it within a range that does not deviate from the principle configuration, but in FIG. 1 and FIG. Since it is drawn as a figure, the shapes of the constituent members are different from those in FIG. The grindstone cover 19 shown in FIGS. 1 and 4 is a member that is installed in a fixed relationship with the blade 1 so that the relative position with respect to the adjusting grindstone member 9 does not change, and the moving arm 14 is It is fixed to the blade 1. In the present embodiment (FIGS. 1 and 4), the adjusting whetstone-shaped member 9 and the grinding whetstone 4 are used.
Both of them are structures that can be driven in the XX 'axis direction. However, for convenience of correspondence with FIG. 3 (schematic diagram) and description of the function and effect, the name of the moving arm 14 will be used in the future without being changed. The grindstone cover 20 shown in FIGS. 1 and 4 is a member installed so that the relative position to the grinding wheel 4 does not change, and the fine adjustment stopper 18 is fixedly installed on the grindstone cover 20. .
The fixed stopper 18 in the present embodiment is the same device as that in which the arcuate arm is removed from the micrometer, and the rod 18a can be finely adjusted to be expanded and contracted. Adjust the fine adjustment stopper 18 to adjust the rod 1
When 8a is extended, the driven portion 16b of the backup lever 16 is pushed to tilt the backup lever 16 about the pivot shaft 15, and the backup shoe 16a causes the ultrafine shaft portion of the ultrafine stepped shaft 8 to grind the grinding wheel 4 It will be strongly pressed toward. When the rod 18a is contracted, the pressing force of the backup shoe 16a is reduced, and when the rod 18a is contracted further, the backup shoe 16a is separated from the ultrafine shaft portion. As can be understood from the above operation, the state in which the backup shoe 16a slides against the fine shaft portion of the fine stepped shaft 8 and presses it toward the grinding wheel 4 is changed by the adjustment of the fine adjustment stopper 18. . If the above pressing force is increased, the grinding efficiency will be improved, but if an excessive pressing force is given, the dimensional accuracy of the grinding finish will decrease, so it is possible to obtain as high efficiency as possible within the range where the required accuracy can be obtained. Adjust to.

In the apparatus of this embodiment, the rotating adjusting grindstone member 9 and the rotating grinding wheel 4 are moved to the X direction.
Finely adjust the stopper 18 by making it relatively close to the −X ′ axis direction.
Rod 18a contacts the backup lever 16 and tilts it, and the backup shoe 16a slides against the extra-fine shaft portion of the extra-fine stepped shaft to back up while the grinding wheel 4 moves to the extra-fine shaft portion. Grinding is started by making contact, but it is difficult for the backup lever 16 to rattle before the rod 18a of the fine adjustment stopper 18 comes into contact with the backup lever 16 (before grinding begins). Therefore, as shown in FIG. Further, a spring 21 is compression-inserted between the backup lever 16 and the moving arm 14. The spring 21 applies a clockwise (clockwise) rotational force to the backup lever 16 in FIG. 4, and a counterclockwise (counterclockwise) rotational force to the backup lever 16 in FIGS. 1 and 3. The backup shoe 16a is provided and the grinding wheel 4 is provided.
It works in the direction of pushing away from.

As shown in FIG. 1, the backup shoe 16a is formed by forming a v-shaped groove having an angle ψ near the lower end of the backup lever 16.

The angle ψ is made obtuse so as to make line contact with the ultrafine shaft along two parallel lines. However, since the ultrafine shaft portion may be tapered, the contact lines along the two parallel lines are not necessarily exactly parallel. In this embodiment, the angle ψ is set to 1
It was set to 20 degrees. The angle ψ of the v-shaped groove is related to the lever ratio of the backup lever 16 as described later. In the present embodiment, the ultrafine stepped shaft 8 which is supported and rotated by the blade 1 and the adjusting grindstone-shaped member 9 is located on the illustrated axis XX '. That is, FIG.
The center height H described in (A) is ground in a state of zero. In this way, in the state where the core height is zero, the direction of the force pressing the extra-fine shaft portion 8b of the extra-fine stepped shaft 8 by the backup lever 16 is toward the center of the grinding wheel 4, so that stable grinding is facilitated and the grinding state is maintained. It is convenient to control.
When the basic principle of the present invention is described above with reference to FIG. 3, the pivot shaft 15 of the backup lever 16 includes the driven portion 16b of the backup lever and the backup shoe 16.
It is described as being located in the center of a. However, in FIG. 1 and FIG. 4 which depict the actual shape of the actual device,
The angle ψ of the v-shaped groove of the backup shoe 16a is 120.
The lever ratio L ₃ /
L ₄ was set to 1.14. In practicing the present invention, good results are generally obtained when the lever ratio is 1.1, that is, when the rounded value is 1.1. In the present invention, the ultrafine stepped shaft 8 which is the workpiece is supported by the blade 1 and the adjusting grindstone member 9, and the extrafine stepping shaft is rotationally driven by the friction transmission of the adjusting grindstone member. In this case, when the pressing roller 22 shown in phantom in FIG. 4 is also used to press the extra fine stepped shaft 8 toward the adjusting grindstone member 9, the extra fine stepped shaft 8 is securely
Moreover, it can be rotated in a stable state, and grinding in a state close to heavy grinding becomes possible.

The present invention is basically based on grinding the ultrafine shaft to a cylindrical surface, but it is also possible to grind and finish the ultrafine taper shaft. In this embodiment, the material of the ultrafine drill is ground and finished, and the ultrafine shaft portion that serves as the cutting edge of the drill is back-tapered. In the case of this example, the taper amount T
Is a trace amount of T = 2.2 micron / 5 millimeter = 44/1000000. In this embodiment (see FIG. 2), the rotation axis of the grinding wheel 4 is 22/1000 as indicated by the arc arrow r ₅ .
The back taper was applied by shaking only 00. As an example different from this, the ultrafine shaft portion 8b can be tapered by forming the side surface 4a (FIG. 2) of the grinding wheel 4 into a tapered surface. Further, the adjusting grindstone shaft may be shaken. When forming a taper on the ultrafine shaft portion, theoretically, it is necessary to incline the groove bottom line of the v-shaped groove of the backup shoe so that the line contact is made evenly with the ultrafine shaft portion. However, in the case where the taper amount is an extremely small amount of 1 / 10,000 unit as in this example, it was experimentally confirmed that no particular problem occurs even if the backup shoe for a straight ultrafine shaft is used.

In the present embodiment, the diameter dimension of the ultrafine shaft portion 8b before grinding is 1.5 mm, and the finishing dimension is 0.25 mm in diameter. The time required for this grinding operation was 31 seconds per piece, which was significantly higher than that of the conventional technique. The working conditions in this embodiment are as follows. Workpiece material: Carbide Workpiece shape and dimensions: As shown in Fig. 6 Diameter of adjusting grindstone member: 115 mm 〃 Rotation speed: 37 rpm 〃 Peripheral speed; 13.4 m / min 〃 Drive motor output: 0.06 kW 〃 Material: A220T3R40 made by Noritake Co., Ltd. Diameter of grinding wheel: 150 mm 〃 Rotation speed: 7639 rpm 〃 Peripheral speed: 3600 m / min 〃 Drive motor output: 0.4 kW 〃 Material: Osaka Diamond Co., Ltd. SD400R100B made
K4 Adjusting whetstone dressing angle: 0 ° Workpiece center height: 0 mm Feed angle: -1 ° Peripheral speed ratio: 269.3 Deletion rate: 0.12 cubic mm / sec Workpiece depth of cut: 1.25 mm Cutting speed: max 0.052 mm / sec Blade thickness: 1.0 millimeter Blade apex angle: 60 ° Brand of grinding fluid: Sunicour Blue (trade name) manufactured by Nippon San Oil Co., Ltd. Further, grinding in this example The accuracy is as follows. Roundness: 0.62 to 1.33 micron Surface roughness: 0.51 to 0.75 micron Deflection: less than 1 micron Concentricity: 0.51 to 0.56 micron The above numbers are the measured values in the test room. However, it shows that the apparatus and method of this embodiment are practically applicable as they are to industrial production.

[0018]

When the present invention is applied, the base shaft portion of the extra fine stepped shaft is rotated by friction transmission while being supported by the adjusting grindstone member and the blade. In this way, since the extra fine stepped shaft is supported by using the cylindrical surface of the outer periphery as a proof, there is no fear that a concentricity error will occur due to a chuck error when attaching a workpiece (extra fine stepped shaft) to the spindle. . Further, since it is not necessary to provide a center hole in the ultrafine shaft portion for centering, the lower limit of the thickness dimension of the ultrafine shaft portion is not restricted in this sense. Further, as described above, since the work piece is supported innocently, there is no fear of being affected by the rotation accuracy of the spindle chucking the work piece, and high accuracy can be obtained. Moreover, the backup shoe is kept in sliding contact with the extra-fine shaft part that is the grinding part, and the contact pressure is kept constant, so high-efficiency grinding is possible, and even if high-efficiency grinding is performed, the extra-fine shaft part is performed. There is no risk of breakage. Since the backup shoe receives the portion to be ground as described above, the portion to be ground does not escape even when the grinding wheel comes into contact therewith, so that the ultrafine shaft portion can be ground with high accuracy.

If a lever mechanism is used as a means for following the backup shoe at a speed 2V which is twice the moving speed V (cutting speed) of the grinding wheel, accurate control can be performed with a simple structure. It is suitable. The above actions work comprehensively to grind ultra-fine stepped shafts with high precision, high efficiency, high yield, without requiring special skill, without fear of human error, and at low cost. It has an excellent practical effect that can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing a grinding apparatus 1 for an ultrafine stepped shaft according to the present invention, which is configured to carry out a method for grinding an ultrafine stepped shaft according to the present invention.
FIG. 6 is an explanatory view showing an embodiment, in which a dimensional symbol and a dimensional line are added to a front view drawn by cutting a part thereof, and a reciprocating arrow indicating an operation is added.

FIG. 2 is a plan view of the external appearance of the adjusting grindstone member, the blade, the ultrafine stepped shaft, and the grinding wheel extracted from the above-mentioned embodiment and separated from each other, and the sectional shape of the backup shoe is added. FIG. 6 is a diagram additionally showing an arrow for explaining the operation and an arc arrow indicating a rotation direction.

FIG. 3 shows one embodiment of the grinding apparatus of the present invention created to carry out the method for grinding an ultrafine stepped shaft according to the present invention,
It is a schematic front view for easy understanding of the structure and action, and is drawn so as to be modified so as to clearly express the connection relationship and relative movement of each component, so that it is not necessarily the case of the embodiment. It is not a projected figure of the actual shape of the device.

FIG. 4 is a back view of the above embodiment.

FIG. 5 shows a conventional example of a centerless grinding machine, (A) is an explanatory view in which dimension symbols and motion symbols are entered in a schematically drawn front view, and (B) is a diagram of a centerless grinding machine for stepped shaft machining. It is the figure which added the work piece to the exploded plan view of the part.

FIG. 6 is a view showing a front view showing an example of an extra-fine stepped shaft which is a workpiece in the embodiment of the present invention, in which dimension symbols and dimension numerical values are added.

FIG. 7 is a schematic view for explaining the difference between uncentered grinding and cored grinding, in which (A) shows a state in which the base shaft portion of the ultrafine stepped shaft is uncentered (centerless grinding),
(B) shows a state in which the fine shaft portion of the fine stepped shaft is ground by a grinding wheel. However, since it is schematically illustrated, the dimensional relationship does not necessarily have a shape in which the substance is uniformly scaled.

[Explanation of symbols]

1 ... Blade, 1a ... Slope on top, 2 ... Adjusting grindstone, 3 ...
Work piece, 4 ... Grinding grindstone, 5 ... Stepped work piece, 6 ... Stepped grindstone, 7 ... Stepped grindstone, 8 ... Extra fine stepped shaft, 8a ... Basic shaft part, 8b ... Extra fine shaft part, 8c ... Tapered portion, 9 ... Adjusting grindstone member, 10 ... Stationary base, 11 ... Stationary bearing, 12 ... Slide base, 13 ... Moving bearing, 14 ... Moving arm, 1
5 ... Pivot shaft, 16 ... Backup lever, 16a ... Backup shoe, 16b ... Driven part, 17 ... Stationary arm,
18 ... Fine adjustment stopper, 18a ... Rod, 19, 20 ...
Grindstone cover, 21 ... Spring, 22 ... Presser roller.

Claims (23)

[Claims] 1. A method for grinding an ultrafine shaft portion of a stepped shaft in which a cylindrical ultrafine shaft and a base shaft having a larger diameter than that are concentrically integrally connected to each other, are the same as or similar to a blade of a centerless grinder. Blade and the adjusting grindstone-like member similar to or similar to the adjusting grindstone of the centerless grinding machine support the portion of the large diameter base shaft of the extra fine stepped shaft, and rotate the adjusted grindstone member to rotate the extra fine stepped shaft. While rotating the blade, without changing the relative position of the blade and the adjusting grindstone member, both of these members are brought closer to the rotating grinding wheel at a speed V, The ultrafine shaft portion of the ultrafine stepped shaft which is supported and rotated by the above member is brought into contact with a grinding wheel to grind the outer peripheral surface of the ultrafine shaft portion, and the ultrafine shaft portion ground as described above. Touch the backup shoe to Together occupied, in the direction allowed to approach the backup shoe grinding wheel, speed of about 2V
A method for grinding an ultra-fine stepped shaft, which is characterized in that it is moved by. 2. The backup lever is supported so as to be tiltable in the vicinity of the center of the backup lever by a fulcrum that is moved at a relative speed V with respect to the grinding wheel together with the blade without changing the relative position with respect to the blade. At the same time, a backup shoe is fixed near one end of the backup lever, and a stopper fixedly installed on the bearing member of the grinding wheel is applied near the other end of the backup lever. By bringing them into contact with each other, when the ultrafine stepped shaft supported by the blade and the adjusting whetstone-shaped member approaches the grinding wheel at a speed V, the backup shoe approaches the grinding wheel at a speed of about 2V. The method for grinding an extra fine stepped shaft according to claim 1. 3. A backup shoe is provided with a v-shaped groove having an obtuse angle at the groove bottom, preferably about 120 degrees, which is parallel to the extra-fine shaft portion, at a position where the backup shoe slides against the extra-fine shaft portion. The method for grinding an ultrafine stepped shaft according to claim 1 or 2, wherein the ultrafine shaft portion is line-contacted along two parallel straight lines. 4. The distance from the fulcrum near the center of the backup lever to the backup shoe is L _4, and the distance from the driven point at which the backup lever abuts the stopper to the fulcrum near the center is L 4. ₃ , the distance L ₄ is set to be substantially equal to the distance L ₃ , preferably L ₄ is set slightly larger than L ₃ , and more preferably the distance L ₄ is about 1.1 times the distance L _3. The method for grinding an ultrafine stepped shaft according to claim 2 or 3, characterized in that: 5. The sliding contact between the backup shoe and the extra-fine shaft portion is achieved by finely adjusting the position of the contact point of the stopper fixedly installed on the bearing member of the grinding wheel with respect to the backup lever. The method for grinding an ultrafine stepped shaft according to any one of claims 2 to 4, wherein the state is adjusted. 6. A tilting force is applied to the backup lever by a spring means to tilt the backup lever in a direction of abutting the stopper to generate a contact pressure. Item 5. A method of grinding an extra fine stepped shaft according to item 5. 7. The adjusting grindstone-like member is made of a material having a friction coefficient larger than that of an abrasive and not having grindability, according to any one of claims 1 to 6. Grinding method for extra fine stepped shaft. 8. The adjusting grindstone member is made of a grinding material so that it can be used also as an adjusting grindstone of a centerless grinder if necessary, and this member is used as the adjusting grindstone to form a base shaft of an extra fine stepped shaft. The method for grinding an ultrafine stepped shaft according to any one of claims 1 to 6, wherein the portion is centerless ground. 9. The pressing roller is brought into contact with a base shaft portion of the extra fine stepped shaft when the backup shoe is brought into contact with the extra fine shaft portion of the extra fine stepped shaft and the extra fine shaft portion is brought into contact with a grinding wheel to perform grinding. 9. The grinding of an extra fine stepped shaft according to any one of claims 1 to 8, characterized in that a pressing force is applied at least to stabilize the support state of the base shaft portion by the blade and the adjusting grindstone member. Method. 10. A rotation axis center line of the adjusting grindstone member, a rotation axis center line of the grinding wheel, and a center line of the ultrafine stepped shaft are aligned on the same horizontal plane, and the ultrafine shaft is provided in a state where the center height is zero. The method for grinding an extra fine stepped shaft according to any one of claims 1 to 9, wherein the portion is ground. 11. A back taper is imparted to the extra-fine shaft portion by inclining a portion where the grinding wheel comes into contact with the extra-fine shaft portion of the extra-fine step shaft by a small angle with respect to the center line of the extra-fine step shaft. The method for grinding an ultrafine stepped shaft according to any one of claims 1 to 10, characterized in that. 12. A blade (1) which supports a base shaft portion (8a) of an ultrafine stepped shaft (8) which is a workpiece and which is similar to a blade of a centerless grinder and an adjustment grindstone of the centerless grinder. A grinding whetstone (4) comprising a similar adjusting whetstone member (9) and comprising a rotary whetstone that comes into contact with the ultrafine shaft portion (8b) of the ultrafine stepped shaft and grinds the same. The backup shoe (16a) for supporting the grinding reaction force by sliding on the shaft portion is provided, and the backup shoe is made to approach the extra-fine shaft portion by following the reduction of the extra-fine shaft portion by grinding. An ultrafine stepped shaft grinding machine, comprising: an interlocking mechanism that keeps the contact pressure between the shoe and the ultrafine shaft part substantially constant. 13. The above-mentioned interlocking mechanism comprises a backup lever (16) having a backup shoe (16a) at one end, and a backup lever (16) near the central portion of the backup grindstone member (9). A pivot shaft (15) pivotally supported on a fulcrum whose relative position with respect to the bearing member does not change, and the grinding wheel (4) is installed so as not to change relative position with respect to the bearing member, and the backup lever of the backup lever is installed. 13. An apparatus for grinding an ultrafine stepped shaft according to claim 12, further comprising a stopper means (18) that abuts on the other end. 14. The backup shoe (16a).
Has a v-shaped groove that is in line contact with the extra-fine shaft portion (8b) along two parallel lines. 14. The extra-fine according to claim 12 or 13, characterized in that Stepping shaft grinding machine. 15. The grinding machine for an extra fine stepped shaft according to claim 14, wherein the pair of surfaces of the v-shaped groove have an obtuse angle, and preferably about 120 degrees. 16. From a pivot shaft (15) pivotally supporting the central portion of the backup lever (16) to a driven portion (16b) on which the backup lever receives abutment of the stopper means (18). the distance between the L _3, the distance between the said pivot shaft to said backup shoe (16a) as L _4, the distance L ₄ described above substantially equal than the distance L _3, or slightly larger, The grinding apparatus for an ultrafine stepped shaft according to any one of claims 13 to 15, which is preferably about 1.1 times. 17. The stopper means (18) has a fine adjustment function for expanding and contracting the backup lever (16) toward a driven portion (16b) which receives the contact of the stopper means. The grinding apparatus for an ultrafine stepped shaft according to any one of claims 13 to 16. 18. The spring according to claim 13, further comprising a spring (21) for giving a tilting force to the backup lever (16) in a direction to bring it into contact with the stopper means. An apparatus for grinding a shaft with an extra fine step described in any one of 1. 19. The adjusting grindstone member (9) is made of a material having a friction coefficient with respect to metal larger than that of an abrasive and not having grindability.
A grinding apparatus for an ultrafine stepped shaft according to any one of claims 12 to 18. 20. The adjusting grindstone member (9) is made of an abrasive material, and is a member that can also be used as an adjusting grindstone of a centerless grinder. An apparatus for grinding a shaft with an extra fine step described in any one of 1. 21. A line contact is made with a base shaft portion (8a) of an ultrafine stepped shaft (8) supported by the blade (1) and the adjusting grindstone member (9), and the base shaft portion is brought into contact. 21. A grinding apparatus for an ultrafine stepped shaft according to any one of claims 12 to 20, further comprising a pressing roller (22) which is pressed against the adjusting grindstone member. 22. The center line of the ultrafine stepped shaft (18) supported by the blade (1) and the adjusting grindstone member (9) is defined by "the centerline of the rotating shaft of the adjusting grindstone member and the grinding wheel". 22. The related member is arranged so as to be located on an "imaginary plane defined by the center line of the rotation axis of (4)". Grinding machine for extra fine stepped shaft. 23. The grinding wheel (4) is adapted to come into line contact with the extra-fine shaft portion (8b) of the extra-fine stepped shaft (8), and the contact line is extra-fine. The grinding apparatus for an ultrafine stepped shaft according to any one of claims 12 to 22, characterized in that it can be tilted by a small angle with respect to the center line of the stepped shaft.