Grinding method and grindstone with shaft

Abstract

A grindstone (10) with a shaft comprises: a base metal (11); a grindstone shaft (12) having one end supported by the base metal (11); and a grindstone (13) attached to the grindstone shaft (12). Guide shapes (15a, 17, 18, 18a) are provided to the base metal (11) so that a grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to a grinding position of a workpiece (1) while changing the flow direction.

Description

Grinding method and mounted grinding wheel

[0001] The present disclosure relates to a grinding method and a mounted grinding wheel.

[0002] Conventionally, in the internal grinding of a workpiece, a mounted grindstone has been used, in which a grindstone is attached to a grindstone spindle that is rotated by a wheel head (see Patent Document 1).

[0003] 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 stopped for several seconds until the bending is eliminated. If the machining hole is long and narrow, the grinding wheel spindle must also be long and narrow. In this case, the rigidity of the grinding wheel spindle decreases, and it takes time for the spark-out to recover the bending of the grinding wheel spindle, which increases the machining time.

[0004] Furthermore, in internal grinding, it is necessary to supply a 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 the 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 so that it follows the axial direction of the grinding wheel spindle, and positioning the grinding fluid nozzle facing the machined hole.

[0005] JP 2014-69303 A

[0006] However, if the grinding wheel spindle is shortened to ensure its rigidity in order to shorten the time required for spark-out and reduce the processing time, the distance between the workpiece and the wheel head becomes too short when grinding the deepest part of the drilled hole, making it difficult to properly position the coolant nozzle.If the grinding fluid cannot be supplied sufficiently to the grinding point, problems such as grinding burn, in which the temperature of the grinding point reaches 500°C or more, or a shortened lifespan of the grinding wheel may occur.

[0007] An object of the present disclosure is to provide a grinding method and a grinding wheel that can shorten the grinding wheel shaft to ensure the rigidity of the grinding wheel shaft while supplying sufficient grinding fluid to the grinding point of the workpiece.

[0008] The first aspect is a grinding method for grinding the internal diameter of a workpiece (1) by rotating a grinding wheel (13) attached to a grinding wheel spindle (12) protruding from a base metal (11), wherein 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 grinding fluid released toward the outer peripheral surface of the base metal (11) is supplied to the grinding point of the workpiece (1) while changing its flow direction due to guide shapes (15a, 17, 18, 18a) provided on the base metal (11).

[0009] In the first 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 shapes (15a, 17, 18, 18a) provided on the base metal (11) allow a sufficient supply of grinding fluid to the grinding location of the workpiece (1). This makes it possible to suppress grinding burn and wear of the grinding wheel (13), thereby extending the life of the shank-mounted grinding wheel.

[0010] In the second embodiment, the inner diameter of the workpiece (1) is ground while the base metal (11) is covered with a non-rotating umbrella-shaped member (21) in the first embodiment.

[0011] In the second aspect, the scattering of grinding fluid from the outer peripheral surface of the base metal (11) can be suppressed, thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

[0012] The third aspect is a shaft-mounted grinding wheel comprising a base metal (11), a grinding wheel spindle (12) having one end supported by the base metal (11), and a grinding wheel (13) attached to the grinding wheel spindle (12) and rotating together with the grinding wheel spindle (12) to grind the internal diameter of a workpiece (1), wherein the base metal (11) is provided with guide shapes (15a, 17, 18, 18a) so that grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding point of the workpiece (1) while changing its flow direction.

[0013] 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 shapes (15a, 17, 18, 18a) provided on the base metal (11) allow a sufficient supply of grinding fluid to the grinding location of the workpiece (1). This prevents grinding burn and reduces wear on the grinding wheel (13), thereby extending the life of the shank-mounted grinding wheel. Furthermore, because the grinding wheel spindle (12) can be shortened, it is possible to prevent a decrease in processing accuracy due to bending of the grinding wheel spindle (12). It is also possible to shorten the time required for spark-out, thereby shortening the processing time, i.e., improving the processing speed.

[0014] In a fourth aspect, in the third aspect, the base metal (11) has a truncated cone portion (15) having the grinding wheel spindle (12) at its top and a cylindrical portion (16) connected to the bottom of the truncated cone portion (15), a concave surface (15a) is provided on the outer peripheral surface of the truncated cone portion (15) as the guide shape (15a, 17, 18, 18a), an inclination angle θ of the concave surface (15a) with respect to the grinding wheel spindle (12) at the top of the truncated cone portion (15) is not less than 0° and not more than 20°, the inclination angle θ increases from the top to the bottom of the truncated cone portion (15), and the concave surface (15a) at the bottom of the truncated cone portion (15) is connected to the outer peripheral surface of the cylindrical portion (16) at an angle φ of not less than 40° and not more than 90°.

[0015] 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, so that the grinding fluid can be supplied from the top of the truncated cone portion 15 along the grinding wheel spindle 12 toward the grinding point of the workpiece 1.

[0016] In the fifth aspect, in the third aspect, the base metal (11) has a truncated cone 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 truncated cone portion (15), and a plurality of twisted blades (17) are provided on the outer peripheral surface of the truncated cone portion (15) as the guide shape (15a, 17, 18, 18a).

[0017] In the fifth aspect, by rotating the plurality of blades (17) together with the base metal (11), the grinding fluid released 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).

[0018] In a 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 grinding wheel spindle (12) at the top of the truncated cone portion (15) is equal to or greater than 0° and equal to or less than 20°, and the inclination angle θ increases from the top to the bottom of the truncated cone portion (15), and the concave surface (15a) at the bottom of the truncated cone portion (15) is connected to the outer peripheral surface of the cylindrical portion (16) at an angle φ of equal to or greater than 40° and equal to or less than 90°.

[0019] In the sixth aspect, in addition to the effects of the fifth aspect, the effects of the fourth aspect can be obtained.

[0020] In a seventh aspect, in the fifth or sixth aspect, a cover member (19) is provided on the truncated cone portion (15) so as to cover the plurality of blades (17).

[0021] In the seventh aspect, the scattering of grinding fluid from the outer peripheral surface of the truncated cone portion (15) can be suppressed, thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

[0022] In the eighth aspect, in the third aspect, the base metal (11) has a truncated cone 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 truncated cone portion (15), and a plurality of twisted grooves (18) are provided on the outer peripheral surface of the truncated cone portion (15) as the guide shapes (15a, 17, 18, 18a).

[0023] In the eighth aspect, by rotating the plurality of 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 along the plurality of grooves (18) 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).

[0024] In a 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 an inclination angle θ of the concave surface (18a) with respect to the grinding wheel spindle (12) at the top of the truncated cone portion (15) is not less than 0° and not more than 20°, and the inclination angle θ increases from the top to the bottom of the truncated cone portion (15), and the concave surface (18a) at the bottom of the truncated cone portion (15) is connected to the outer peripheral surface of the cylindrical portion (16) at an angle φ of not less than 40° and not more than 90°.

[0025] In the ninth aspect, the injection pressure of the grinding fluid can be utilized 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, i.e., the concave surface (18a), of the groove (18) of the truncated cone portion (15), thereby enabling the grinding fluid to be supplied more efficiently toward the grinding point of the workpiece (1).

[0026] In a tenth aspect, in the eighth or ninth aspect, a cover member (19) is provided on the truncated cone portion (15) so as to cover the plurality of grooves (18).

[0027] In the tenth aspect, the scattering of grinding fluid from the outer peripheral surface of the truncated cone portion (15) can be suppressed, thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding point of the workpiece (1).

[0028] FIG. 1 is a perspective view of a grinding device equipped with a mounted grindstone according to an embodiment. FIG. 2 is a cross-sectional view of a grinding device equipped with a mounted grindstone according to an embodiment. FIG. 3 is a perspective view of the mounted grindstone according to an embodiment. FIG. 4 is a side view of the mounted grindstone according to an embodiment (viewed from a direction perpendicular to the grindstone axis). FIG. 5 is a perspective view of a mounted grindstone according to Modification 1. FIG. 6 is a perspective view of a mounted grindstone according to Modification 2. FIG. 7 is a perspective view of a mounted grindstone according to Modification 3. FIG. 8 is a side view of a grinding device equipped with a mounted grindstone according to Modification 4 (viewed from a direction perpendicular to the grindstone axis). 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.

[0029] (Embodiments) Hereinafter, 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 concept of the present disclosure. Since the drawings are intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding. Specific numerical values ​​of various parameters described in the following embodiments are merely examples and are not intended to be limiting.

[0030] <Configuration of Shaft-Mounted Grindstone> As shown in Figures 1 to 4, the grinding device (100) mainly includes a shaft-mounted grindstone (10) that grinds the internal diameter of the workpiece (1), a wheel head (20) that rotates the shaft-mounted grindstone (10), and a grinding fluid supply unit (30) that supplies grinding fluid to the grinding point of the workpiece (1).

[0031] The mounted grinding wheel (10) includes a metal base (11), an elongated grinding wheel stalk (12) with one end supported by the base (11), and a grinding wheel (13) replaceably attached to the grinding wheel stalk (12). The base (11) has, for example, a truncated cone portion (15) with the grinding wheel stalk (12) attached to its top, and a cylindrical portion (16) connected to the bottom of the truncated cone portion (15). The cylindrical portion (16) may be chamfered to fit a wrench for attachment to a wheel head (20). The grinding wheel stalk (12) may be integrally molded from the same material as the base (11). If the rigidity of the grinding wheel stalk (12) needs to be increased, the grinding wheel stalk (12) made of a superhard material may be inserted and joined to the base (11). The grinding wheel 13 may have, for example, a cylindrical shape and be fixed to the grinding wheel spindle 12 with the grinding wheel spindle 12 inserted into a cylindrical hole in the grinding wheel 13. The grinding wheel 13 rotates together with the grinding wheel spindle 12 to grind the inner diameter of the workpiece 1. The diameter of the grinding wheel 13 is several millimeters smaller than the diameter of the hole to be formed in the workpiece 1.

[0032] The base metal (11) of the mounted grinding wheel (10) has a fixing member (14) on the opposite side of the grinding wheel stalk (12) for attaching the mounted grinding wheel (10) to a rotation mechanism (not shown) of a wheel head (20). The fixing member (14) may be, for example, a mounting screw or a lead-in taper (fastener). The wheel head (20) is configured so that the mounted grinding wheel (10) can be advanced and retreated in the axial direction of the grinding wheel stalk (12).

[0033] The grinding fluid jetting port (31) of the grinding fluid supply unit (30) is arranged so as to be able to spray the grinding fluid onto the outer peripheral surface of the base metal (11) of the mounted 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 jetting port (31) in a direction perpendicular to the grinding wheel shaft (12), or may supply the grinding fluid in a direction inclined from the perpendicular direction toward the grinding wheel (13). The piping to the grinding fluid jetting port (31) in the grinding fluid supply unit (30) may be arranged along the outer wall (non-rotating portion) of the wheel head (20).

[0034] In the grinding device (100), the grindstone (13) may be rotated at a high speed while the workpiece (1) is rotated at a low speed. In this case, the workpiece (1) may be held on a rotatable work table. Instead of or in addition to the configuration in which the mounted grindstone (10) is advanced or retreated together with the wheel head (20) in the axial direction of the grindstone spindle (12), the workpiece (1) may be advanced or retreated together with the work table that holds the workpiece (1) in the axial direction of the grindstone spindle (12).

[0035] <Guide Shape> In internal grinding of a workpiece (1), a grinding wheel (13) is inserted into a recess (machined hole) provided in the workpiece (1) and the grinding wheel (13) is rotated to grind the inner surface of the machined hole. The grinding wheel (13) inserted into the machined hole in the workpiece (1) is movable in the axial direction of the grinding wheel spindle (12) and also in the radial direction of the grinding wheel spindle (12). This allows the inner surface of the machined hole to be machined into a desired shape.

[0036] 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 stalk (12), changing the distance between the base metal (11) and the workpiece (1) (the end face of the workpiece (1) facing the base metal (11)). In this embodiment, a mounted grindstone (10) with a short grindstone stalk (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 portion of the hole in the workpiece (1) with the grindstone (13) while avoiding contact between the base metal (11) and the workpiece (1). Therefore, the flow direction of the grinding fluid released toward the outer peripheral surface of the base metal (11) is changed by guide shapes (15a, 17, 18, 18a) provided on the base metal (11), and the grinding fluid is supplied to the grinding point of the workpiece (1). In other words, the base metal (11) is provided with guide shapes (15a, 17, 18, 18a) so that the grinding fluid sprayed toward the outer peripheral surface of the base metal (11) can be supplied to the grinding location of the workpiece (1) while changing its flow direction. The guide shapes (15a, 17, 18, 18a) supply the grinding fluid sprayed onto the outer peripheral surface of the base metal (11) to the grinding wheel spindle (12) and grinding wheel (13) located closer to the inner diameter side against centrifugal force while ensuring maximum rigidity of the grinding wheel spindle (12) and the base metal (11). The guide shapes (15a, 17, 18, 18a) change 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 port (31) to the direction of the grinding location of the workpiece (1).

[0037] Specifically, as shown in Fig. 4, a concave surface 15a may be provided on the outer peripheral surface of the truncated cone portion 15 of the base metal 11 as a guide shape 15a, 17, 18, 18a. The inclination angle θ of the concave surface 15a with respect to the grinding wheel spindle 12 (the central axis J of the grinding wheel spindle 12) is between 0° and 20° at the top of the truncated cone portion 15. 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 connects to the outer peripheral surface of the cylindrical portion 16 at an angle φ between 40° and 90°. The angle φ is equal to the inclination angle of the concave surface 15a at the bottom of the truncated cone portion 15 with respect to the central axis J of the grinding wheel spindle 12.

[0038] The shape of the base metal (11) is a combination of a truncated cone portion (15) having an outer peripheral surface at 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 mounted grinding wheel (10) is viewed from a direction perpendicular to the grinding wheel shaft (12), a curve (for example, a parabola or arc) that is a concave surface (15a) 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 grinding wheel (13), and the inclination angle θ with the grinding wheel shaft (12) is about 0 to 20°, and the inclination angle θ changes significantly toward the bottom of the truncated cone portion (15). The curved line is connected to the outer peripheral surface of a cylindrical portion (16) having a diameter larger than that of the grinding wheel (13) at an angle φ of 40° to 90°.

[0039] In the shape of the base metal (11) shown in Figure 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). However, 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.

[0040] 4, the angle of inclination 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 released 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. Also, since the angle of inclination θ of the concave surface 15a at the top of the truncated cone portion 15 relative to the grinding wheel shaft 12 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.

[0041] In addition, in the shape of the base metal (11) shown in Figure 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 when grinding fluid is released toward the outer peripheral surface of the truncated cone portion (15)—specifically, toward the outer peripheral surface near the bottom of the truncated cone portion (15)—from a direction perpendicular or approximately perpendicular to the grinding wheel shaft (12) (the central axis J of the grinding wheel shaft (12)—the grinding fluid is less likely to bounce back from the outer peripheral surface of the base metal (11). This improves 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 location where the grinding fluid from the grinding fluid ejection port (31) directly hits and the spray angle of the grinding fluid from the grinding fluid ejection port (31) (angle with respect to the grinding wheel spindle (12)) becomes smaller. Therefore, if the spray 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 location where the grinding fluid from the grinding fluid ejection port (31) directly hits may be between 70° and 90°.

[0042] <Modifications of Guide Shape> [Modification 1] As shown in Modification 1 in Fig. 5 , a plurality of twisted blades (17) may be provided as guide shapes (15a, 17, 18, 18a) on the outer peripheral surface of the truncated cone portion (15) of the base metal (11). The plurality of blades (17) extend from the top to the bottom of the truncated cone portion (15) so as to be twisted in the rotation direction of the mounted grindstone (10), i.e., the base metal (11). In this way, by rotating the plurality of blades (17) together with the base metal (11), grinding fluid released toward the outer peripheral surface of the base metal (11) can flow toward the grinding wheel spindle (12) along the outer peripheral surface of the base metal (11) between the blades (17) against centrifugal force. Therefore, the grinding fluid can be released from the top of the truncated cone portion (15) in a direction along the grinding wheel shaft (12), and 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).

[0043] 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 grinding wheel spindle (12) (central axis J) is between 0° and 20° at the top of the truncated cone portion (15). 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) connects to the outer peripheral surface of the cylindrical portion (16) at an angle φ between 40° and 90°. In this way, in addition to the above-described effects, the same effects as those in the embodiment shown in Fig. 4 can be obtained.

[0044] 5, the truncated cone portion 15 of the metal base 11 may have a plurality of blades 17 on its outer peripheral surface without providing a concave surface 15a. The above-described effects can also be achieved in this case. The plurality of blades 17 may be provided only on a portion of the truncated cone portion 15 between its top and bottom, for example, only near its top.

[0045] [Variation 2] As shown in Variation 2 in Fig. 6, a plurality of twisted grooves (18) may be provided as guide shapes (15a, 17, 18, 18a) on the outer peripheral surface of the truncated cone portion (15) of the base metal (11). The plurality of grooves (18) extend from the top to the bottom of the truncated cone portion (15) in a twisted manner in the rotation direction of the mounted grindstone (10), i.e., the base metal (11). In this way, by rotating the plurality of grooves (18) together with the base metal (11), grinding fluid released toward the outer peripheral surface of the base metal (11) can flow along the plurality of grooves (18) toward the grinding wheel spindle (12) against centrifugal force. Therefore, the grinding fluid can be released from the top of the truncated cone portion 15 in a direction along the grinding wheel shaft 12, so that 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. The configuration of Modification 2 shown in Figure 6 corresponds to the configuration of Modification 1 shown in Figure 5 in which the width (width in the rotation direction) of the multiple blades 17 is increased.

[0046] In addition, in the second modification shown in Fig. 6, a concave surface (18a) may be further provided on the bottom surface of the plurality of grooves (18) as a guide shape (15a, 17, 18, 18a). The inclination angle θ of the concave surface (18a) with respect to the grinding wheel spindle (12) (central axis J) is between 0° and 20° at the top of the truncated cone portion (15). 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 (18a) connects to the outer peripheral surface of the cylindrical portion (16) at an angle φ between 40° and 90°. In other words, the concave surface (18a) that is the bottom surface of the plurality of 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 Fig. 4, the grinding fluid sprayed toward the outer peripheral surface of the base metal 11 can be made to flow easily along the grooves 18 of the truncated cone portion 15 by utilizing the injection pressure of the grinding fluid, thereby significantly achieving the above-mentioned effect. In this case, if the outer peripheral surface of the truncated cone portion 15 between the grooves 18 is also formed into 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, scattering of the grinding fluid can be further suppressed, thereby more significantly achieving the above-mentioned effect.

[0047] 6, the recessed surfaces 18a may not be provided on the bottom surfaces of the grooves 18. Even in this case, the above-described effects can be obtained. The grooves 18 may be provided only in a portion of the truncated cone portion 15 between the top and the bottom, for example, only in the vicinity of the top.

[0048] [Variation 3] Variation 3 shown in FIG. 7 differs from Variation 1 shown in FIG. 5 in that a cover member (19) is provided on the truncated cone portion (15) so as to cover the plurality of blades (17). The cover member (19) may be joined to the plurality of blades (17) by brazing. The cover member (19) may be provided so as to cover a portion of each of the plurality of blades (17). When the cover member (19) is provided, grinding fluid is supplied to the outer peripheral surface of the truncated cone portion (15) through a gap between the cover member (19) and the cylindrical portion (16). This prevents 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 location of the workpiece (1).

[0049] In the second modification shown in Fig. 6, a cover member similar to the cover member (19) of the third modification may be provided on the truncated cone portion (15) so as to cover the grooves (18). This can provide the same effect as the third modification.

[0050] [Variation 4] Variation 4 shown in Fig. 8 differs from Variation 3 shown in Fig. 7 in that, instead of the cover member 19 provided on the truncated cone portion 15, the outer peripheral surface of the base metal 11 (particularly the truncated cone portion 15) is covered by a non-rotating umbrella-shaped member 21 attached via an arm to the outer wall (non-rotating portion) of the wheel head 20. When the umbrella-shaped member 21 is provided, grinding fluid is supplied to the outer peripheral surface of the truncated cone portion 15 through the gap between the umbrella-shaped member 21 and the wheel head 20. This prevents the grinding fluid from scattering from the truncated cone portion 15, i.e., the outer peripheral surface of the base metal 11, thereby enhancing the effect of concentrating and supplying the grinding fluid to the grinding location of the workpiece 1.

[0051] In addition, in the modified example 4 shown in Figure 8, an umbrella-shaped member (21) is provided to cover the outer peripheral surface of the base metal (11) of modified example 1 shown in Figure 5, but similarly, an umbrella-shaped member (21) may be provided to cover the outer peripheral surface of the base metal (11) of the embodiment shown in Figure 4 or the outer peripheral surface of the base metal (11) of modified example 2 shown in Figure 6.

[0052] <Features of the embodiment (including modified examples)> The grinding method of the embodiment is a grinding method for grinding the inner diameter of a workpiece (1) by rotating a grinding wheel (13) attached to a grinding wheel spindle (12) protruding from a base metal (11). The distance between the base metal (11) and the workpiece (1) changes during grinding, and when the innermost part of the workpiece (1) is ground, the distance is 5 mm or less. The grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding point of the workpiece (1) while changing its flow direction due to guide shapes (15a, 17, 18, 18a) provided on the base metal (11).

[0053] In the grinding method of the embodiment, even if the grinding wheel shank (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 shapes (15a, 17, 18, 18a) provided on the base metal (11) allow a sufficient supply of grinding fluid to the grinding location of the workpiece (1). This prevents grinding burn and reduces wear on the grinding wheel (13), thereby extending the life of the shank-mounted grinding wheel (10). Furthermore, because the grinding wheel shank (12) can be shortened, it is possible to prevent a decrease in processing accuracy due to bending of the grinding wheel shank (12). It is also possible to shorten the time required for spark-out, thereby shortening the processing time, i.e., improving the processing speed.

[0054] 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 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).

[0055] The mounted grindstone (10) of this embodiment includes 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 inner diameter of a workpiece (1). Guide shapes (15a, 17, 18, 18a) are provided on the base metal (11) so that grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding location of the workpiece (1) while changing its flow direction.

[0056] In the mounted grindstone (10) of this embodiment, even if the grindstone shank (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 shapes (15a, 17, 18, 18a) provided on the base metal (11) allow a sufficient supply of grinding fluid to the grinding location of the workpiece (1). This prevents grinding burn and reduces wear on the grindstone (13), thereby extending the life of the mounted grindstone. Furthermore, because the grindstone shank (12) can be shortened, it is possible to prevent a decrease in machining accuracy due to bending of the grindstone shank (12). This also reduces the time required for spark-out, thereby shortening the machining time, i.e., improving the machining speed.

[0057] On the other hand, when the grinding fluid supply pipe is bent along the axial direction of the grinding wheel spindle and the grinding fluid nozzle is positioned toward the machined hole as in the conventional case, if the grinding wheel spindle (12) is long as in Comparative Example 1 shown in Fig. 9, the grinding fluid nozzle (31) can be positioned toward the machined 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 positioned toward the machined hole. Note that in Comparative Examples 1 and 2 shown in Figs. 9 and 10, the same elements as in the embodiment shown in Fig. 2 are denoted by the same reference numerals. As mentioned above, it is desirable to make the grinding wheel spindle as short as possible to ensure rigidity, but if 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 will block the machined hole in the workpiece, making it impossible to properly position the grinding fluid nozzle. This can result in an insufficient supply of grinding fluid to the grinding point of the workpiece, causing problems such as grinding burn that causes the temperature of the grinding point to reach 500°C or higher, and shortening the life of the grinding wheel.

[0058] In the embodiment of the mounted grindstone (10), the base metal (11) has a truncated cone portion (15) with a grindstone shaft (12) attached to its top, and a cylindrical portion (16) connected to the bottom of the truncated cone portion (15), and a concave surface (15a) may be provided on the outer peripheral surface of the truncated cone portion (15) as a guide shape (15a, 17, 18, 18a). At the top of the truncated cone portion (15), the inclination angle θ of the concave surface (15a) relative to the grindstone shaft (12) is between 0° and 20°, 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 between 40° and 90°. In this way, 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 outer peripheral surface of the truncated cone portion 15, i.e., the concave surface 15a. In addition, since the inclination of the concave surface 15a at the top of the truncated cone portion 15 relative to the grinding wheel spindle 12 is gentle, the grinding fluid can be supplied from the top of the truncated cone portion 15 along the grinding wheel spindle 12 toward the grinding point of the workpiece 1.

[0059] In the embodiment of the mounted grinding wheel (10), the base metal (11) has a truncated cone portion (15) with a grinding wheel shank (12) at its top and a cylindrical portion (16) connected to the bottom of the truncated cone portion (15). The truncated cone portion (15) may have a plurality of twisted blades (17) formed as guides (15a, 17, 18, 18a) on its outer peripheral surface. By rotating the blades (17) together with the base metal (11), the grinding fluid released toward the outer peripheral surface of the base metal (11) can flow toward the grinding wheel shank (12) along the outer peripheral surface of the base metal (11) against centrifugal force. Therefore, the grinding fluid can be supplied from the top of the truncated cone portion (15) along the grinding wheel shank (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 multiple blades (17). At the top of the truncated cone portion (15), the inclination angle θ of the concave surface (15a) relative to the grinding wheel spindle (12) is between 0° and 20°, and 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) connects to the outer peripheral surface of the cylindrical portion (16) at an angle φ between 40° and 90°. In this way, 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), thereby more efficiently supplying the grinding fluid to the grinding point of the workpiece (1). Furthermore, 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 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).

[0060] In the embodiment of the mounted grinding wheel (10), the base metal (11) has a truncated cone portion (15) with a grinding wheel shank (12) at its top and a cylindrical portion (16) connected to the bottom of the truncated cone portion (15), and a plurality of twisted grooves (18) may be formed on the outer peripheral surface of the truncated cone portion (15) as guide shapes (15a, 17, 18, 18a). In this way, by rotating the plurality of grooves (18) together with the base metal (11), the grinding fluid discharged toward the outer peripheral surface of the base metal (11) can flow along the plurality of grooves (18) toward the grinding wheel shank (12) against centrifugal force, so that the grinding fluid can be supplied from the top of the truncated cone portion (15) along the grinding wheel shank (12) toward the grinding point of the workpiece (1). In this case, a concave surface (18a) may be further provided on the bottom surface of each of the plurality of grooves (18) as a guide shape (15a, 17, 18, 18a). The inclination angle θ of the concave surface (18a) at the top of the truncated cone portion (15) relative to the grinding wheel spindle (12) is between 0° and 20°, and 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 (18a) connects to the outer circumferential surface of the cylindrical portion (16) at an angle φ between 40° and 90°. This configuration allows the grinding fluid released toward the outer circumferential surface of the truncated cone portion (15) of the base metal (11) to flow along the bottom surface of the groove (18), i.e., the concave surface (18a), thereby more efficiently supplying the grinding fluid to the grinding point of the workpiece (1). Furthermore, 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).

[0061] (Other Embodiments) In the above-described embodiment and modified examples, the concave surfaces (15a, 18a), the blades (17), and the grooves (18) provided on the outer peripheral surface of the truncated cone portion (15) have been exemplified as the guide shapes (15a, 17, 18, 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 location of the workpiece (1) while changing its flow direction.

[0062] Although the embodiments and modifications have been described above, it will be understood that various modifications in 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.

[0063] As described above, the present disclosure is useful for a grinding method and a mounted grinding wheel.

[0064] DESCRIPTION OF SYMBOLS 1 Workpiece 10 Shaft-mounted grinding stone 11 Base metal 12 Grinding stone spindle 13 Grinding stone 15 Circular 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 Cover member 21 Umbrella-shaped member

Claims

1. A grinding method for grinding the internal diameter of a workpiece (1) by rotating a grindstone (13) attached to a grindstone spindle (12) protruding from a base metal (11), wherein 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 grinding fluid discharged toward the outer peripheral surface of the base metal (11) is supplied to the grinding point of the workpiece (1) while changing its flow direction due to guide shapes (15a, 17, 18, 18a) provided on the base metal (11).

2. The grinding method according to claim 1, wherein the internal diameter of the workpiece (1) is ground while the base metal (11) is covered with a non-rotating umbrella-shaped member (21).

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

4. A grinding wheel with a shaft as claimed in claim 3, wherein the base metal (11) has a conical frustum portion (15) having the grinding wheel shaft (12) at its top, and a cylindrical portion (16) connected to the bottom of the conical frustum portion (15), a concave surface (15a) is provided on the outer peripheral surface of the conical frustum portion (15) as the guide shape (15a, 17, 18, 18a), an inclination angle θ of the concave surface (15a) with respect to the grinding wheel shaft (12) at the top of the conical frustum portion (15) is between 0° and 20°, the inclination angle θ increases from the top to the bottom of the conical frustum portion (15), and the concave surface (15a) at the bottom of the conical frustum portion (15) is connected to the outer peripheral surface of the cylindrical portion (16) at an angle φ between 40° and 90°.

5. The shaft-mounted grinding wheel of claim 3, wherein the base metal (11) has a conical frustum portion (15) having the grinding wheel shaft (12) at its top, and a cylindrical portion (16) connected to the bottom of the conical frustum portion (15), and a plurality of twisted blades (17) are provided on the outer circumferential surface of the conical frustum portion (15) as the guide shape (15a, 17, 18, 18a).

6. A grinding wheel with a shaft as claimed in claim 5, wherein 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), an inclination angle θ of the concave surface (15a) with respect to the grinding wheel shaft (12) at the top of the truncated cone portion (15) is not less than 0° and not more than 20°, 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 not less than 40° and not more than 90°.

7. The grinding wheel according to claim 5 or 6, wherein a cover member (19) is provided on the truncated cone portion (15) so as to cover the plurality of blades (17).

8. The shaft-mounted grinding wheel of claim 3, wherein the base metal (11) has a conical frustum portion (15) having the grinding wheel shaft (12) at its top, and a cylindrical portion (16) connected to the bottom of the conical frustum portion (15), and a plurality of twisted grooves (18) are provided on the outer circumferential surface of the conical frustum portion (15) as the guide shape (15a, 17, 18, 18a).

9. A shaft-mounted grinding wheel as claimed in claim 8, wherein a concave surface (18a) is further provided as the guide shape (15a, 17, 18, 18a) on the bottom surface of the plurality of grooves (18), an inclination angle θ of the concave surface (18a) with respect to the grinding wheel shaft (12) at the apex of the truncated cone portion (15) is not less than 0° and not more than 20°, the inclination angle θ increases from the apex to the bottom of the truncated cone portion (15), and 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 not less than 40° and not more than 90°.

10. The shaft grinding wheel according to claim 8 or 9, wherein a cover member (19) is provided on the truncated cone portion (15) so as to cover the plurality of grooves (18).

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