JP7662958B2 - Grinding method and grinding wheel - Google Patents

Description

This disclosure relates to a grinding method and a grinding wheel.

Conventionally, for internal grinding of workpieces, a grinding wheel with a shaft attached to a grinding wheel spindle rotated by a wheel head has been used (see Patent Document 1).

In internal grinding, the grinding load is applied to the grinding wheel, causing the grinding wheel spindle to bend. This bending is significant compared to the machining precision required for grinding, so for high-precision internal grinding, it is necessary to perform a spark-out, in which the axial movement of the grinding wheel spindle is halted for several seconds until the bending disappears. If the machining hole is long and narrow, the grinding wheel spindle used must also be long and narrow. In that case, the rigidity of the grinding wheel spindle decreases, and it takes time for the spark-out to restore the bending of the grinding wheel spindle, resulting in longer machining times.

In addition, in internal grinding, it is necessary to supply grinding fluid to the grinding point of the workpiece. When machining a small, elongated hole, it is necessary to position the grinding fluid nozzle so that the grinding fluid can easily enter the gap between the grinding wheel spindle and the machined hole. If the machined hole is a blind hole, it is necessary to supply grinding fluid to the grinding point of the workpiece from the same side as the grinding wheel spindle. Patent Document 1 discloses bending the grinding fluid supply pipe to follow the axial direction of the grinding wheel spindle, and positioning the grinding fluid nozzle toward the machined hole.

JP 2014-69303 A

However, if an attempt is made to shorten the grinding wheel spindle to ensure its rigidity in order to shorten the time required for spark out and thereby shorten the processing time, the distance between the workpiece and the wheel head becomes too short when grinding the deepest part of the machining hole, making it difficult to properly position the grinding fluid nozzle. If an adequate supply of grinding fluid cannot be supplied to the grinding point, problems such as grinding burn, in which the temperature of the grinding point reaches 500°C or higher, or a shortened lifespan of the grinding wheel can occur.

The objective of this disclosure is to provide a grinding method and a grinding wheel with a shaft that can shorten the grinding wheel shaft to ensure its rigidity while providing a sufficient supply of grinding fluid to the grinding point of the workpiece.

The first aspect is a grinding method for grinding the inner diameter of a workpiece (1) by rotating a grindstone (13) attached to a grindstone shaft (12) protruding from a base metal (11), in which the distance between the base metal (11) and the workpiece (1) changes during grinding, and the distance is 5 mm or less when grinding the innermost part of the workpiece (1), and the grinding fluid discharged toward the outer periphery of the base metal (11) is supplied to the grinding point of the workpiece (1) while changing the flow direction due to guide shapes (15a, 17, 18, 18a) provided on the base metal (11).

In the first embodiment, even if the grindstone shaft (12) is shortened so that the distance between the base metal (11) and the workpiece (1) during grinding is 5 mm or less, the guide shape (15a, 17, 18, 18a) provided on the base metal (11) allows sufficient supply of grinding fluid to the grinding point of the workpiece (1). This makes it possible to suppress grinding burn and to suppress wear of the grindstone (13), thereby extending the life of the grindstone with shaft.

In the second embodiment, the internal diameter of the workpiece (1) is ground while the base metal (11) is covered by a non-rotating umbrella-shaped member (21) in the first embodiment.

In the second embodiment, the grinding fluid can be prevented from scattering from the outer peripheral surface of the base metal (11), thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

The third aspect is a shaft-mounted grindstone comprising a base metal (11), a grindstone spindle (12) one end of which is supported by the base metal (11), and a grindstone (13) attached to the grindstone spindle (12) and rotating together with the grindstone spindle (12) to grind the internal diameter of a workpiece (1). The base metal (11) is provided with a guide shape (15a, 17, 18, 18a) so that the grinding fluid discharged toward the outer circumferential surface of the base metal (11) is supplied to the grinding point of the workpiece (1) while changing its flow direction.

In the third aspect, even if the grinding wheel spindle (12) is shortened so that the distance between the base metal (11) and the workpiece (1) during grinding is 5 mm or less, the guide shape (15a, 17, 18, 18a) provided on the base metal (11) allows sufficient supply of grinding fluid to the grinding point of the workpiece (1). This makes it possible to suppress grinding burn and to suppress wear of the grinding wheel (13), thereby extending the life of the shaft-mounted grinding wheel. In addition, since the grinding wheel spindle (12) can be shortened, it is possible to suppress a decrease in processing accuracy caused by bending of the grinding wheel spindle (12), and it is possible to shorten the time required for spark out, thereby shortening the processing time, i.e., improving the processing speed.

In the fourth aspect, in the third aspect, the base metal (11) has a conical truncated portion (15) with the grinding wheel shaft (12) at its top and a cylindrical portion (16) connected to the bottom of the conical truncated portion (15), and a concave surface (15a) is provided on the outer peripheral surface of the conical truncated portion (15) as the guide shape (15a, 17, 18, 18a), and the inclination angle θ of the concave surface (15a) with respect to the grinding wheel shaft (12) at the top of the conical truncated portion (15) is 0° or more and 20° or less, and the inclination angle θ increases from the top to the bottom of the conical truncated portion (15), and at the bottom of the conical truncated portion (15), the concave surface (15a) is connected to the outer peripheral surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less.

In the fourth aspect, the injection pressure of the grinding fluid can be used to make the grinding fluid discharged toward the outer peripheral surface of the truncated cone portion (15) of the base metal (11) flow along the concave surface (15a). This allows the grinding fluid to be supplied from the top of the truncated cone portion (15) along the grinding wheel shaft (12) toward the grinding point of the workpiece (1).

In the fifth aspect, in the third aspect, the base metal (11) has a conical truncated portion (15) at the top of which the grinding wheel shaft (12) is provided, and a cylindrical portion (16) connected to the bottom of the conical truncated portion (15), and a plurality of twisted blades (17) are provided on the outer circumferential surface of the conical truncated portion (15) as the guide shape (15a, 17, 18, 18a).

In the fifth embodiment, by rotating the blades (17) together with the base metal (11), the grinding fluid discharged toward the outer peripheral surface of the base metal (11) can be made to flow along the outer peripheral surface of the base metal (11) toward the grinding wheel shaft (12) against the centrifugal force, so that the grinding fluid can be supplied from the top of the truncated cone portion (15) along the grinding wheel shaft (12) toward the grinding point of the workpiece (1).

In the sixth aspect, in the fifth aspect, a concave surface (15a) is further provided as the guide shape (15a, 17, 18, 18a) on the outer peripheral surface of the truncated cone portion (15) between the plurality of blades (17), and the inclination angle θ of the concave surface (15a) with respect to the grindstone shaft (12) at the apex of the truncated cone portion (15) is 0° or more and 20° or less, the inclination angle θ increases from the apex to the bottom of the truncated cone portion (15), and at the bottom of the truncated cone portion (15), the concave surface (15a) is connected to the outer peripheral surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less.

In the sixth aspect, in addition to the effects of the fifth aspect, the effects of the fourth aspect can be obtained.

The seventh aspect is the fifth or sixth aspect, in which a cover member (19) is provided on the truncated cone portion (15) so as to cover the plurality of blades (17).

In the seventh aspect, the grinding fluid can be prevented from scattering from the outer peripheral surface of the truncated cone portion (15), thereby improving the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

The eighth aspect is the third aspect, in which the base metal (11) has a conical truncated portion (15) at the top of which the grinding wheel shaft (12) is provided, and a cylindrical portion (16) connected to the bottom of the conical truncated portion (15), and a plurality of twisted grooves (18) are provided on the outer circumferential surface of the conical truncated portion (15) as the guide shape (15a, 17, 18, 18a).

In the eighth aspect, by rotating the multiple grooves (18) together with the base metal (11), the grinding fluid discharged toward the outer peripheral surface of the base metal (11) can be made to flow toward the grinding wheel shaft (12) along the multiple grooves (18) against centrifugal force, so that the grinding fluid can be supplied from the top of the truncated cone portion (15) along the grinding wheel shaft (12) toward the grinding point of the workpiece (1).

In the ninth aspect, in the eighth aspect, a concave surface (18a) is further provided on the bottom surface of the plurality of grooves (18) as the guide shape (15a, 17, 18, 18a), and the inclination angle θ of the concave surface (18a) with respect to the grindstone shaft (12) at the apex of the truncated cone portion (15) is 0° or more and 20° or less, the inclination angle θ increases from the apex to the bottom of the truncated cone portion (15), and at the bottom of the truncated cone portion (15), the concave surface (18a) is connected to the outer circumferential surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less.

In the ninth aspect, the injection pressure of the grinding fluid can be used to make the grinding fluid released toward the outer peripheral surface of the truncated cone portion (15) of the base metal (11) flow along the bottom surface of the groove (18) of the truncated cone portion (15), i.e., the concave surface (18a), so that the grinding fluid can be more efficiently supplied toward the grinding point of the workpiece (1).

The tenth aspect is the eighth or ninth aspect, in which a cover member (19) is provided on the truncated cone portion (15) so as to cover the multiple grooves (18).

In the tenth aspect, the grinding fluid can be prevented from scattering from the outer peripheral surface of the truncated cone portion (15), thereby improving the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

FIG. 1 is a perspective view of a grinding device including a mounted grindstone according to an embodiment. FIG. 2 is a cross-sectional view of a grinding device including a mounted grindstone according to an embodiment. FIG. 3 is a perspective view of a mounted grindstone according to the embodiment. FIG. 4 is a side view of the mounted grindstone according to the embodiment (as viewed from a direction perpendicular to the grindstone axis). FIG. 5 is a perspective view of a mounted grindstone according to the first modified example. FIG. 6 is a perspective view of a mounted grindstone according to the second modification. FIG. 6 is a perspective view of a grindstone according to the third modified example. FIG. 8 is a side view (viewed from a direction perpendicular to the grindstone axis) of a grinding device equipped with a mounted grindstone according to Modification 4. In FIG. FIG. 9 is a cross-sectional view of a grinding device equipped with a mounted grindstone according to Comparative Example 1. FIG. 10 is a cross-sectional view of a grinding device equipped with a mounted grindstone according to Comparative Example 2.

(Embodiment)
Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical idea of the present disclosure. Since each drawing is intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding. The specific numerical values of various parameters described in the following embodiments are merely examples and are not limited thereto.

<Configuration of the mounted grindstone>
As shown in Figures 1 to 4, the grinding device (100) mainly comprises a shaft-mounted grindstone (10) for grinding the internal diameter of a workpiece (1), a wheel head (20) for rotating the shaft-mounted grindstone (10), and a grinding fluid supply unit (30) for supplying grinding fluid to the grinding point of the workpiece (1).

The grinding wheel (10) includes a metal base (11), an elongated grinding wheel shaft (12) with one end supported by the base (11), and a grinding wheel (13) attached to the grinding wheel shaft (12) in an exchangeable manner. The base (11) has, for example, a conical truncated portion (15) with the grinding wheel shaft (12) at its top, and a cylindrical portion (16) connected to the bottom of the conical truncated portion (15). The cylindrical portion (16) may be chamfered for a wrench for attachment to the wheel head (20). The grinding wheel shaft (12) may be integrally molded from the same material as the base (11). If it is desired to increase the rigidity of the grinding wheel shaft (12), the grinding wheel shaft (12) made of a super-hard material may be inserted and joined to the base (11). The grindstone (13) may have, for example, a cylindrical shape and be fixed to the grindstone spindle (12) with the grindstone spindle (12) inserted into a cylindrical hole in the grindstone (13). The grindstone (13) rotates together with the grindstone spindle (12) to grind the inner diameter of the workpiece (1). The diameter of the grindstone (13) is several mm smaller than the diameter of the hole to be formed in the workpiece (1).

The base metal (11) of the grinding wheel (10) has a fixing member (14) on the opposite side of the grinding wheel shaft (12) for attaching the grinding wheel (10) to a rotation mechanism (not shown) of the wheel head (20). The fixing member (14) may be, for example, a mounting screw or a retractable taper (fastener). The wheel head (20) is configured so that the grinding wheel (10) can be advanced and retreated in the axial direction of the grinding wheel shaft (12).

The grinding fluid supply unit (30) has a grinding fluid nozzle (31) arranged so that it can eject the grinding fluid onto the outer peripheral surface of the base metal (11) of the axle grinding wheel (10), specifically onto the outer peripheral surface of the truncated cone portion (15). The grinding fluid supply unit (30) may supply the grinding fluid from the grinding fluid nozzle (31) in a direction perpendicular to the grinding wheel shaft (12), or may supply the grinding fluid in a direction inclined toward the grinding wheel (13) from the perpendicular direction. The piping to the grinding fluid nozzle (31) in the grinding fluid supply unit (30) may be arranged along the outer wall (non-rotating portion) of the wheel head (20).

In the grinding device (100), the grindstone (13) may be rotated at high speed while the workpiece (1) is rotated at low speed. In this case, the workpiece (1) may be held on a rotatable worktable. Instead of or in addition to the configuration in which the shaft-mounted grindstone (10) is advanced or retreated in the axial direction of the grindstone spindle (12) together with the wheel head (20), the workpiece (1) may be advanced or retreated in the axial direction of the grindstone spindle (12) together with the worktable that holds the workpiece (1).

<Guide shape>
In internal grinding of a workpiece (1), a grindstone (13) is inserted into a recess (machined hole) provided in the workpiece (1) and rotated to grind the inner surface of the machined hole. The grindstone (13) inserted into the machined hole in the workpiece (1) is movable in the axial direction of the grindstone shaft (12) and also in the radial direction of the grindstone shaft (12). This allows the inner surface of the machined hole to be machined into a desired shape.

In the grinding method of this embodiment, when grinding the inner diameter of the workpiece (1), the grindstone (13) is moved in the axial direction of the grindstone shaft (12), so that the distance between the base metal (11) and the workpiece (1) (the end face of the workpiece (1) on the base metal (11) side) changes. In this embodiment, a shaft-mounted grindstone (10) with a short grindstone shaft (12) is used so that the distance between the base metal (11) and the workpiece (1) is 5 mm or less when grinding the innermost part of the machining hole of the workpiece (1) with the grindstone (13) while avoiding contact between the base metal (11) and the workpiece (1). Therefore, the grinding fluid is supplied to the grinding part of the workpiece (1) while changing the flow direction of the grinding fluid discharged toward the outer peripheral surface of the base metal (11) by the guide shape (15a, 17, 18, 18a) provided on the base metal (11). In other words, the base metal (11) is provided with a guide shape (15a, 17, 18, 18a) so that the grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding part of the workpiece (1) while changing its flow direction. The guide shape (15a, 17, 18, 18a) supplies the grinding fluid sprayed onto the outer peripheral surface of the base metal (11) to the grinding wheel shaft (12) and grinding wheel (13) located on the inner diameter side against centrifugal force while ensuring maximum rigidity of the grinding wheel spindle (12) and base metal (11). The guide shape (15a, 17, 18, 18a) changes the flow direction of the grinding fluid on the outer peripheral surface of the base metal (11) from the spray direction of the grinding fluid from the grinding fluid spray nozzle (31) to the direction of the grinding part of the workpiece (1).

Specifically, as shown in FIG. 4, a concave surface (15a) may be provided as a guide shape (15a, 17, 18, 18a) on the outer peripheral surface of the truncated cone portion (15) of the base metal (11). The inclination angle θ of the concave surface (15a) with respect to the grinding wheel shaft (12) (the central axis J of the grinding wheel shaft (12)) is 0° or more and 20° or less at the top of the truncated cone portion (15), and the inclination angle θ increases from the top to the bottom of the truncated cone portion (15), and at the bottom of the truncated cone portion (15), the concave surface (15a) connects to the outer peripheral surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less. The angle φ is equal to the inclination angle of the concave surface (15a) with respect to the central axis J of the grinding wheel shaft (12) at the bottom of the truncated cone portion (15).

The shape of the base metal (11) is a combination of a truncated cone portion (15) having an outer peripheral surface with an inclination angle of, for example, 45° with respect to the bottom surface, and a cylindrical portion (16) into which a fixing member (14) for the wheel head (20) is inserted, but in the example shown in Figure 4, the outer peripheral surface of the truncated cone portion (15) is replaced with a curved concave surface (15a). As shown in Figure 4, when the wheel-mounted grindstone (10) is viewed from a direction perpendicular to the grindstone shaft (12), a curve (for example, a parabola or arc) that is a concave surface (15a) with an inclination angle θ of about 0 to 20° with respect to the grindstone shaft (12) begins to extend from the top of the truncated cone portion (15) that has a diameter slightly (for example, about 1 to 2 mm) larger than the diameter of the grindstone (13), and the inclination angle θ changes significantly toward the bottom of the truncated cone portion (15). The curve connects to the outer peripheral surface of the cylindrical portion (16), which has a larger diameter than the grindstone (13), at an angle φ of 40° or more and 90° or less.

In the shape of the base metal (11) shown in FIG. 4, the rigidity of the base metal (11) is slightly reduced compared to when the outer peripheral surface of the truncated cone portion (15) is not made concave (15a), but compared to the effect of improving rigidity by shortening the grinding wheel spindle (11), the reduction in rigidity of the base metal (11) is small enough to not be a problem.

On the other hand, in the shape of the base metal (11) shown in FIG. 4, the inclination angle θ of the concave surface (15a) on the outer peripheral surface of the truncated cone portion (15) relative to the grinding wheel shaft (12) increases from the top to the bottom of the truncated cone portion (15), so that the grinding fluid discharged toward the outer peripheral surface of the truncated cone portion (15) of the base metal (11) can be made to flow along the concave surface (15a) by utilizing the injection pressure of the grinding fluid. In addition, since the inclination angle θ of the concave surface (15a) relative to the grinding wheel shaft (12) at the top of the truncated cone portion (15) is gentle, ranging from 0° to 20°, the grinding fluid can be supplied from the top of the truncated cone portion (15) along the grinding wheel shaft (12) toward the grinding point of the workpiece (1).

In addition, in the shape of the base metal (11) shown in FIG. 4, the inclination angle θ of the concave surface (15a) relative to the grinding wheel shaft (12) increases from the top to the bottom of the truncated cone portion (15), and at the bottom of the truncated cone portion (15), the concave surface (15a) connects to the outer peripheral surface of the cylindrical portion (16) at an angle φ of 40° to 90°. Therefore, even if the grinding fluid is discharged toward the outer peripheral surface of the truncated cone portion (15) in a direction perpendicular or approximately perpendicular to the grinding wheel shaft (12) (the central axis J of the grinding wheel shaft (12)), specifically toward the outer peripheral surface near the bottom of the truncated cone portion (15), the grinding fluid is less likely to bounce back from the outer peripheral surface of the base metal (11). This can enhance the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1). This effect increases as the difference between the inclination angle θ of the concave surface (15) of the truncated cone portion (15) at the point where the grinding fluid from the grinding fluid ejection port (31) hits directly and the injection angle of the grinding fluid from the grinding fluid ejection port (31) (angle with respect to the grinding wheel shaft (12)) becomes smaller. Therefore, if the injection angle of the grinding fluid is 90° or close to 90°, the inclination angle θ of the concave surface (15) of the truncated cone portion (15) at the point where the grinding fluid from the grinding fluid ejection port (31) hits directly may be 70° or more and 90° or less.

<Modifications of the guide shape>
[Variation 1]
As shown in the first modified example in Fig. 5, a plurality of twisted blades (17) may be provided as guide shapes (15a, 17, 18, 18a) on the outer circumferential surface of the truncated cone portion (15) of the base metal (11). The blades (17) extend from the top to the bottom of the truncated cone portion (15) so as to be twisted in the direction of rotation of the shaft-mounted grindstone (10), i.e., the base metal (11). In this way, by rotating the blades (17) together with the base metal (11), the grinding fluid discharged toward the outer circumferential surface of the base metal (11) can flow toward the grindstone shaft (12) against centrifugal force along the outer circumferential surface of the base metal (11) between the blades (17). Therefore, since the grinding fluid can be released from the top of the truncated cone portion (15) in a direction along the grinding wheel shaft (12), the grinding fluid can be supplied to the grinding wheel (13), i.e., the grinding point of the workpiece (1), through the gap between the machining hole in the workpiece (1) and the grinding wheel shaft (12).

In the first modification shown in FIG. 5, a concave surface (15a) may be further provided as a guide shape (15a, 17, 18, 18a) on the outer peripheral surface of the truncated cone portion (15) between the plurality of blades (17). The inclination angle θ of the concave surface (15a) with respect to the grindstone shaft (12) (center axis J) is 0° or more and 20° or less at the top of the truncated cone portion (15), and the inclination angle θ increases from the top to the bottom of the truncated cone portion (15), and at the bottom of the truncated cone portion (15), the concave surface (15a) is connected to the outer peripheral surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less. In this way, in addition to the above-mentioned effects, the same effects as those in the embodiment shown in FIG. 4 can be obtained.

In addition, in the first modified example shown in FIG. 5, multiple vanes (17) may be provided on the outer peripheral surface of the truncated cone portion (15) of the base metal (11) without providing a concave surface (15a) on the outer peripheral surface. Even in this case, the above-mentioned effect can be obtained. Furthermore, the multiple vanes (17) may be provided only in a portion between the top and bottom of the truncated cone portion (15), for example, only near the top.

[Variation 2]
As shown in the second modification in FIG. 6, a plurality of twisted grooves (18) may be provided as guide shapes (15a, 17, 18, 18a) on the outer circumferential surface of the truncated cone portion (15) of the base metal (11). The grooves (18) extend from the top to the bottom of the truncated cone portion (15) so as to be twisted in the direction of rotation of the shank grindstone (10), i.e., the base metal (11). By rotating the grooves (18) together with the base metal (11), the grinding fluid discharged toward the outer circumferential surface of the base metal (11) can flow toward the grindstone shaft (12) along the grooves (18) against the centrifugal force. Therefore, the grinding fluid can be discharged from the top of the truncated cone portion (15) in the direction along the grindstone shaft (12), so that the grinding fluid can be supplied to the grindstone (13), i.e., the grinding part of the workpiece (1), through the gap between the processing hole of the workpiece (1) and the grindstone shaft (12). The configuration of the second modified example shown in FIG. 6 corresponds to the configuration of the first modified example shown in FIG. 5, in which the width (width in the direction of rotation) of the plurality of blades (17) is increased.

In addition, in the second modification shown in FIG. 6, a concave surface (18a) may be further provided as a guide shape (15a, 17, 18, 18a) on the bottom surface of the multiple grooves (18). The inclination angle θ of the concave surface (18a) with respect to the grinding wheel shaft (12) (center axis J) is 0° or more and 20° or less at the top of the truncated cone portion (15), and the inclination angle θ increases from the top to the bottom of the truncated cone portion (15), and at the bottom of the truncated cone portion (15), the concave surface (18a) connects to the outer peripheral surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less. That is, the concave surface (18a), which is the bottom surface of the multiple grooves (18), has a curved shape similar to the concave surface (15a) provided on the outer peripheral surface of the truncated cone portion (15) in the embodiment shown in FIG. 4. In this way, for the same reason as in the embodiment shown in Figure 4, the grinding fluid sprayed toward the outer circumferential surface of the base metal (11) can be easily caused to flow along the grooves (18) of the truncated cone portion (15) by utilizing the injection pressure of the grinding fluid, and the above-mentioned effect is more pronounced. In this case, if the outer circumferential surface of the truncated cone portion (15) between the grooves (18) is also given a curved shape similar to the concave surface (15a) provided on the outer circumferential surface of the truncated cone portion (15) in the embodiment shown in Figure 4, scattering of the grinding fluid can be further suppressed, and the above-mentioned effect is more pronounced.

In addition, in the second modification shown in FIG. 6, the bottom surfaces of the grooves (18) do not have to have a concave surface (18a). Even in this case, the above-mentioned effect can be obtained. In addition, the grooves (18) may be provided only in a part of the area between the top and bottom of the truncated cone portion (15), for example, in the vicinity of the top.

[Variation 3]
The third modification shown in FIG. 7 differs from the first modification shown in FIG. 5 in that a cover member (19) is provided on the truncated cone portion (15) so as to cover the blades (17). The cover member (19) may be joined to the blades (17) by brazing. The cover member (19) may be provided so as to cover a portion of each of the blades (17). When the cover member (19) is provided, the grinding fluid is supplied to the outer circumferential surface of the truncated cone portion (15) through a gap between the cover member (19) and the cylindrical portion (16). This can prevent the grinding fluid from scattering from the outer circumferential surface of the truncated cone portion (15), thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

In addition, in the second modification shown in FIG. 6, a cover member similar to the cover member (19) in the third modification may be provided on the truncated cone portion (15) so as to cover the multiple grooves (18). This can provide the same effect as the third modification.

[Variation 4]
The fourth modification shown in Fig. 8 differs from the third modification shown in Fig. 7 in that, instead of the cover member (19) provided on the truncated cone portion (15), a non-rotating umbrella-shaped member (21) attached via an arm to the outer wall (non-rotating portion) of the wheel head (20) covers the outer circumferential surface of the base metal (11) (particularly the truncated cone portion (15)). When the umbrella-shaped member (21) is provided, the grinding fluid is supplied to the outer circumferential surface of the truncated cone portion (15) through the gap between the umbrella-shaped member (21) and the wheel head (20). This makes it possible to prevent the grinding fluid from scattering from the truncated cone portion (15), i.e., the outer circumferential surface of the base metal (11), thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

In addition, in the fourth modification shown in FIG. 8, an umbrella-shaped member (21) is provided to cover the outer peripheral surface of the base metal (11) of the first modification shown in FIG. 5, but an umbrella-shaped member (21) may be provided to cover the outer peripheral surface of the base metal (11) of the embodiment shown in FIG. 4 or the outer peripheral surface of the base metal (11) of the second modification shown in FIG. 6 in a similar manner.

<Features of the embodiment (including modifications)>
The grinding method of the embodiment is a grinding method for grinding the inner diameter of a workpiece (1) by rotating a grindstone (13) attached to a grindstone spindle (12) protruding from a base metal (11). The distance between the base metal (11) and the workpiece (1) during grinding changes, and the distance is 5 mm or less when grinding the innermost part of the workpiece (1). Grinding fluid discharged toward the outer circumferential surface of the base metal (11) is supplied to the grinding part of the workpiece (1) while changing the flow direction due to guide shapes (15a, 17, 18, 18a) provided on the base metal (11).

In the grinding method of the embodiment, even if the grindstone shaft (12) is shortened so that the distance between the base metal (11) and the workpiece (1) during grinding is 5 mm or less, the guide shape (15a, 17, 18, 18a) provided on the base metal (11) allows sufficient supply of grinding fluid to the grinding point of the workpiece (1). This makes it possible to suppress grinding burn and to suppress wear of the grindstone (13), thereby extending the life of the shaft-mounted grindstone (10). In addition, since the grindstone shaft (12) can be shortened, it is possible to suppress a decrease in processing accuracy caused by bending of the grindstone shaft (12), and to shorten the time required for spark out, thereby shortening the processing time, i.e., improving the processing speed.

In the grinding method of the embodiment, when the internal diameter of the workpiece (1) is ground while the base metal (11) is covered with a non-rotating umbrella-shaped member (21), the grinding fluid is prevented from scattering from the outer peripheral surface of the base metal (11), which enhances the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

The shaft-mounted grinding wheel (10) of the embodiment includes a base metal (11), a grinding wheel shaft (12) whose one end is supported by the base metal (11), and a grinding wheel (13) that is attached to the grinding wheel shaft (12) and rotates together with the grinding wheel shaft (12) to grind the inner diameter of the workpiece (1). The base metal (11) is provided with guide shapes (15a, 17, 18, 18a) so that the grinding fluid discharged toward the outer circumferential surface of the base metal (11) is supplied to the grinding point of the workpiece (1) while changing its flow direction.

In the embodiment of the grindstone (10), even if the grindstone shaft (12) is shortened so that the distance between the base metal (11) and the workpiece (1) during grinding is 5 mm or less, the guide shape (15a, 17, 18, 18a) on the base metal (11) allows sufficient supply of grinding fluid to the grinding point of the workpiece (1). This makes it possible to suppress grinding burn and to suppress wear of the grindstone (13), thereby extending the life of the grindstone. In addition, since the grindstone shaft (12) can be shortened, it is possible to suppress a decrease in processing accuracy caused by bending of the grindstone shaft (12), and it is possible to shorten the time required for spark out, thereby shortening the processing time, i.e., improving the processing speed.

On the other hand, when the grinding fluid supply pipe is bent along the axial direction of the grinding wheel spindle as in the conventional method and the grinding fluid nozzle is arranged facing the machining hole, if the grinding wheel spindle (12) is long as in Comparative Example 1 shown in FIG. 9, the grinding fluid nozzle (31) can be arranged facing the machining hole, but if the grinding wheel spindle (12) is short as in Comparative Example 2 shown in FIG. 10, the grinding fluid nozzle (31) cannot be arranged facing the machining hole. In Comparative Examples 1 and 2 shown in FIG. 9 and FIG. 10, the same elements as those in the embodiment shown in FIG. 2 are given the same symbols. As mentioned above, it is desirable to make the grinding wheel spindle as short as possible to ensure rigidity, but when the distance between the base metal or wheel head of the grinding wheel spindle and the workpiece is about 5 mm or less, the base metal or wheel head blocks the machining hole of the workpiece as in Comparative Example 2 shown in FIG. 10, so the grinding fluid nozzle cannot be arranged appropriately. This can result in an insufficient supply of grinding fluid to the grinding points of the workpiece, causing problems such as grinding burns that cause the grinding points to reach temperatures of 500°C or higher and shortening the lifespan of the grinding wheel.

In the embodiment of the grindstone (10), the base metal (11) has a conical frustum portion (15) with a grindstone shaft (12) at its top and a cylindrical portion (16) connected to the bottom of the conical frustum portion (15), and a concave surface (15a) may be provided on the outer circumferential surface of the conical frustum portion (15) as a guide shape (15a, 17, 18, 18a). At the top of the conical frustum portion (15), the inclination angle θ of the concave surface (15a) with respect to the grindstone shaft (12) is 0° or more and 20° or less, and the inclination angle θ increases from the top to the bottom of the conical frustum portion (15), and at the bottom of the conical frustum portion (15), the concave surface (15a) is connected to the outer circumferential surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less. In this way, the grinding fluid discharged toward the outer peripheral surface of the truncated cone portion (15) of the base metal (11) can be made to flow along the outer peripheral surface of the truncated cone portion (15), i.e., the concave surface (15a). In addition, because the inclination of the concave surface (15a) relative to the grindstone shaft (12) at the top of the truncated cone portion (15) is gentle, the grinding fluid can be supplied from the top of the truncated cone portion (15) along the grindstone shaft (12) toward the grinding point of the workpiece (1).

In the embodiment of the grinding wheel (10), the base metal (11) has a conical truncated portion (15) with the grinding wheel shaft (12) at its top and a cylindrical portion (16) connected to the bottom of the conical truncated portion (15). The outer peripheral surface of the conical truncated portion (15) may be provided with a plurality of twisted blades (17) as guide shapes (15a, 17, 18, 18a). In this way, by rotating the plurality of blades (17) together with the base metal (11), the grinding fluid discharged toward the outer peripheral surface of the base metal (11) can flow toward the grinding wheel shaft (12) along the outer peripheral surface of the base metal (11) against the centrifugal force. Therefore, the grinding fluid can be supplied from the top of the conical truncated portion (15) along the grinding wheel shaft (12) toward the grinding point of the workpiece (1). In this case, a concave surface (15a) may be further provided as a guide shape (15a, 17, 18, 18a) on the outer peripheral surface of the truncated cone portion (15) between the plurality of blades (17). At the top of the truncated cone portion (15), the inclination angle θ of the concave surface (15a) with respect to the grindstone shaft (12) is 0° or more and 20° or less, and the inclination angle θ increases from the top to the bottom of the truncated cone portion (15), and at the bottom of the truncated cone portion (15), the concave surface (15a) is connected to the outer peripheral surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less. In this way, the grinding fluid discharged toward the outer peripheral surface of the truncated cone portion (15) of the base metal (11) can be made to flow along the concave surface (15a) by utilizing the injection pressure of the grinding fluid, so that the grinding fluid can be more efficiently supplied to the grinding point of the workpiece (1). In addition, by providing a cover member (19) on the truncated cone portion (15) so as to cover the multiple blades (17), it is possible to prevent the grinding fluid from scattering from the outer peripheral surface of the truncated cone portion (15), thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

In the embodiment of the grinding wheel (10), the base metal (11) has a conical truncated portion (15) with the grinding wheel shaft (12) at its top and a cylindrical portion (16) connected to the bottom of the conical truncated portion (15). The outer peripheral surface of the conical truncated portion (15) may have a plurality of twisted grooves (18) as guide shapes (15a, 17, 18, 18a). In this way, by rotating the grooves (18) together with the base metal (11), the grinding fluid discharged toward the outer peripheral surface of the base metal (11) can flow toward the grinding wheel shaft (12) along the grooves (18) against centrifugal force, so that the grinding fluid can be supplied from the top of the conical truncated portion (15) along the grinding wheel shaft (12) toward the grinding point of the workpiece (1). In this case, a concave surface (18a) may be further provided as a guide shape (15a, 17, 18, 18a) on the bottom surface of the plurality of grooves (18). At the top of the truncated cone portion (15), the inclination angle θ of the concave surface (18a) with respect to the grindstone shaft (12) is 0° or more and 20° or less, and the inclination angle θ increases from the top to the bottom of the truncated cone portion (15), and at the bottom of the truncated cone portion (15), the concave surface (18a) is connected to the outer circumferential surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less. In this way, the grinding fluid discharged toward the outer circumferential surface of the truncated cone portion (15) of the base metal (11) can be made to flow along the bottom surface of the groove (18), i.e., the concave surface (18a), by utilizing the injection pressure of the grinding fluid, so that the grinding fluid can be more efficiently supplied to the grinding point of the workpiece (1). In addition, by providing a cover member (19) on the truncated cone portion (15) so as to cover the multiple grooves (18), it is possible to prevent the grinding fluid from scattering from the outer peripheral surface of the truncated cone portion (15), thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

Other Embodiments
In the above-described embodiment and modified examples, the concave surfaces (15a, 18a), the vanes (17), and the grooves (18) provided on the outer peripheral surface of the truncated cone portion (15) are exemplified as the guide shapes (15a, 17, 18a). However, the present invention is not limited to these, and other guide shapes may be provided on the base metal (11) so that the grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding portion of the workpiece (1) while changing its flow direction.

Although the embodiments and modifications have been described above, it will be understood that various modifications of form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate.

As described above, the present disclosure is useful for grinding methods and mounted grinding wheels.

REFERENCE SIGNS LIST 1 workpiece 10 grindstone with shaft 11 base metal 12 grindstone shaft 13 grindstone 15 truncated cone portion 15a concave surface (guide shape)
16 Cylindrical portion 17 Blade (guide shape)
18 Groove (guide shape)
18a Concave surface (guide shape)
19 Lid member 21 Umbrella-shaped member

Claims (9)

A grinding method for grinding an inner diameter of a workpiece (1) by rotating a grindstone (13) attached to a grindstone spindle (12) protruding from a base metal (11), comprising the steps of:
The distance between the base metal (11) and the workpiece (1) during grinding changes, and the distance is 5 mm or less when the innermost portion of the workpiece (1) is ground.
The grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding portion of the workpiece (1) while changing its flow direction due to guide shapes (15a, 17, 18, 18a) provided on the base metal (11) ;
The base metal (11) is
a truncated cone portion (15) having the grindstone shaft (12) mounted at its top;
a cylindrical portion (16) connected to the bottom of the truncated cone portion (15);
having
a concave surface (15a), a plurality of twisted blades (17), or a plurality of twisted grooves (18) are provided on an outer circumferential surface of the truncated cone portion (15) as the guide shape (15a, 17, 18, 18a);
an inclination angle θ of the concave surface (15a) at the apex of the truncated cone portion (15) with respect to the grindstone spindle (12) is equal to or greater than 0° and is equal to or smaller than 20°;
The inclination angle θ increases from the apex to the bottom of the truncated cone portion (15),
At the bottom of the truncated cone portion (15), the concave surface (15a) is connected to the outer circumferential surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less.
Grinding method. 2. The grinding method according to claim 1,
The inner diameter of the workpiece (1) is ground while the base metal (11) is covered with a non-rotating umbrella-shaped member (21).
Grinding method. Base metal (11) and
a grindstone spindle (12) having one end supported by the base metal (11);
a grindstone (13) attached to the grindstone spindle (12) and rotating together with the grindstone spindle (12) to grind the inner diameter of the workpiece (1);
Equipped with
a guide shape (15a, 17, 18, 18a) is provided on the base metal (11) so that the grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding portion of the workpiece (1) while changing its flow direction;
The base metal (11) is
a truncated cone portion (15) having the grindstone shaft (12) mounted at its top;
a cylindrical portion (16) connected to the bottom of the truncated cone portion (15),
a concave surface (15a) is provided on an outer circumferential surface of the truncated cone portion (15) as the guide shape (15a, 17, 18, 18a),
an inclination angle θ of the concave surface (15a) at the apex of the truncated cone portion (15) with respect to the grindstone spindle (12) is equal to or greater than 0° and is equal to or smaller than 20°;
The inclination angle θ increases from the apex to the bottom of the truncated cone portion (15),
At the bottom of the truncated cone portion (15), the concave surface (15a) is connected to the outer circumferential surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less.
Shafted whetstone. Base metal (11) and
a grindstone spindle (12) having one end supported by the base metal (11);
a grindstone (13) attached to the grindstone spindle (12) and rotating together with the grindstone spindle (12) to grind the inner diameter of the workpiece (1);
Equipped with
a guide shape (15a, 17, 18, 18a) is provided on the base metal (11) so that the grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding portion of the workpiece (1) while changing its flow direction;
The base metal (11) is
a truncated cone portion (15) having the grindstone shaft (12) mounted at its top;
a cylindrical portion (16) connected to the bottom of the truncated cone portion (15),
a plurality of twisted blades (17) are provided on an outer circumferential surface of the truncated cone portion (15) as the guide shape (15a, 17, 18, 18a);
Shafted whetstone. The grindstone according to claim 4 ,
a concave surface (15a) is further provided as the guide shape (15a, 17, 18, 18a) on an outer circumferential surface of the truncated cone portion (15) between the plurality of blades (17),
an inclination angle θ of the concave surface (15a) at the apex of the truncated cone portion (15) with respect to the grindstone spindle (12) is equal to or greater than 0° and is equal to or smaller than 20°;
The inclination angle θ increases from the top to the bottom of the truncated cone portion (15),
At the bottom of the truncated cone portion (15), the concave surface (15a) is connected to the outer circumferential surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less.
Shafted whetstone. The grindstone according to claim 4 or 5 ,
A cover member (19) is provided on the truncated cone portion (15) so as to cover the plurality of blades (17).
Shafted whetstone. Base metal (11) and
a grindstone spindle (12) having one end supported by the base metal (11);
a grindstone (13) attached to the grindstone spindle (12) and rotating together with the grindstone spindle (12) to grind the inner diameter of the workpiece (1);
Equipped with
a guide shape (15a, 17, 18, 18a) is provided on the base metal (11) so that the grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding portion of the workpiece (1) while changing its flow direction;
The base metal (11) is
a truncated cone portion (15) having the grindstone shaft (12) mounted at its top;
a cylindrical portion (16) connected to the bottom of the truncated cone portion (15),
A plurality of twisted grooves (18) are provided on the outer circumferential surface of the truncated cone portion (15) as the guide shape (15a, 17, 18, 18a).
Shafted whetstone. The grindstone according to claim 7 ,
a concave surface (18a) is further provided as the guide shape (15a, 17, 18, 18a) on a bottom surface of the plurality of grooves (18),
an inclination angle θ of the concave surface (18a) at the apex of the truncated cone portion (15) with respect to the grindstone spindle (12) is equal to or greater than 0° and is equal to or smaller than 20°;
The inclination angle θ increases from the apex to the bottom of the truncated cone portion (15),
the concave surface (18a) at the bottom of the truncated cone portion (15) is connected to the outer circumferential surface of the cylindrical portion (16) at an angle φ of 40° or more and 90° or less;
Shafted whetstone. The grindstone according to claim 7 or 8 ,
A cover member (19) is provided on the truncated cone portion (15) so as to cover the plurality of grooves (18).
Shafted whetstone.