Grinding method and grinding apparatus

Abstract

To enable grinding liquid to be sufficiently supplied to a ground portion of a work-piece, while securing rigidity of a grindstone shaft by shortening the grindstone shaft, in grinding an inner diameter of the work-piece.SOLUTION: A grinding device (100) rotates a grindstone (13) mounted on a grindstone shaft (12) protruding from a base metal (11) to grind an inner diameter of a work-piece (1). A jetting unit (21) that jets grinding liquid is installed to cover an outer peripheral surface of the base metal (11). A jetting hole (22) is formed in the jetting unit (21) so that grinding liquid discharged from the jetting unit (21) can be supplied to a ground portion of the work-piece (1).SELECTED DRAWING: Figure 8

Description

Technical Field

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

Background Art

[0002] Conventionally, for a grinding apparatus that performs internal diameter grinding of a workpiece, a wheel with a shaft having a grinding wheel attached to a grinding wheel shaft rotated by a wheel head has been used (see Patent Document 1).

[0003] In internal diameter grinding, since a grinding load is applied to the grinding wheel, deflection occurs in the grinding wheel shaft. This deflection is of a magnitude that cannot be ignored compared to the machining accuracy required for grinding. Therefore, for high-precision internal diameter grinding, it is necessary to perform spark out, which stops the axial movement of the grinding wheel shaft for several seconds until this deflection disappears. When the machined hole is elongated, a correspondingly elongated grinding wheel shaft is required. In that case, the rigidity of the grinding wheel shaft becomes low, and since it takes time for spark out to recover the deflection of the grinding wheel shaft, the machining time becomes long.

[0004] Also, in internal diameter grinding, it is necessary to supply grinding fluid to the grinding location of the workpiece. When machining a small-diameter elongated hole, it is necessary to arrange the injection port of the grinding fluid so that the grinding fluid can enter well into the gap between the grinding wheel shaft and the machined hole. If the machined hole is a blind hole, it is necessary to supply the grinding fluid from the same side as the grinding wheel shaft to the grinding location of the workpiece. Patent Document 1 discloses bending the supply pipe of the grinding fluid along the axial direction of the grinding wheel shaft and arranging the injection port of the grinding fluid toward the machined hole.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, if the grinding wheel spindle is shortened to reduce the time required for spark-out and thus shorten the machining time, and the rigidity of the grinding wheel spindle is maintained, 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 sufficient grinding fluid cannot be supplied to the grinding area, problems such as grinding burn where the temperature of the grinding area reaches 500°C or a shortened lifespan of the grinding wheel may occur.

[0007] The purpose of this disclosure is to provide a grinding method and a grinding apparatus that can supply sufficient grinding fluid to the grinding area of ​​the workpiece while ensuring the rigidity of the grinding wheel spindle by shortening the spindle length. [Means for solving the problem]

[0008] The first 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 shaft (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 when grinding the innermost part of the workpiece (1) is 5 mm or less, and grinding fluid released from a spray unit (21) installed to cover the outer circumferential surface of the base metal (11) is supplied to the grinding area of ​​the workpiece (1).

[0009] In the first embodiment, 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, sufficient grinding fluid can be supplied to the grinding area of ​​the workpiece (1) from the injection unit (21) covering the outer surface of the base metal (11). As a result, grinding burn can be suppressed, and wear of the grinding wheel (13) can be suppressed, extending the lifespan of the mounted grinding wheel.

[0010] The second embodiment is a grinding apparatus for grinding the inner diameter of a workpiece (1) by rotating a grinding wheel (13) attached to a grinding wheel shaft (12) protruding from a base metal (11), the apparatus comprising a spray unit (21) installed so as to cover the outer circumferential surface of the base metal (11) and spraying grinding fluid, the spray unit (21) being provided with a spray hole (22) so that the grinding fluid released from the spray unit (21) is supplied to the grinding area of ​​the workpiece (1).

[0011] In the second embodiment, 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, sufficient grinding fluid can be supplied to the grinding area of ​​the workpiece (1) from the injection holes (22) of the injection unit (21) that covers the outer surface of the base metal (11). As a result, grinding burn can be suppressed, and wear of the grinding wheel (13) can be suppressed, extending the lifespan of the mounted grinding wheel.

[0012] In the third embodiment, as in the second embodiment, a plurality of small holes (22) with a diameter of 2 mm or less are arranged near the outer circumferential surface of the base metal (11) as the injection holes (22).

[0013] In the third embodiment, since multiple small-diameter holes (22) are arranged near the outer surface of the base metal (11), the grinding fluid released from each hole (22) can easily enter the gap between the inner wall surface of the machined hole in the workpiece (1) and the grinding wheel spindle (12), making it easier to supply grinding fluid to the grinding area of ​​the workpiece (1).

[0014] A fourth aspect is that, in the third aspect, the inclination angle α of the centerlines of the plurality of holes (22) with respect to the grinding wheel axis (12) is 20 degrees or less, and the plurality of holes (22) are drilled such that the extension of the centerlines strikes the outer circumferential surface of the grinding wheel (13).

[0015] In the fourth embodiment, grinding fluid can be efficiently supplied to the grinding area of ​​the workpiece (1) from the gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel spindle (12).

[0016] Aspect 5 is such that in any one of Aspects 2 to 4, the base metal (11) has a frustum of a cone portion (15) provided with the grinding wheel shaft (12) at the top, and at the top of the frustum of a cone portion (15), the inclination angle θ of the outer peripheral surface of the frustum of a cone portion (15) with respect to the grinding wheel shaft (12) is 0° or more and 20° or less.

[0017] In Aspect 5, in the injection unit (21) covering the outer peripheral surface of the frustum of a cone portion (15), it becomes easy to provide the injection holes (22) in the direction of the grinding portion of the workpiece (1).

Brief Description of Drawings

[0018] [Figure 1] FIG. 1 is a side view of the grinding apparatus according to the embodiment (a view seen from a direction perpendicular to the grinding wheel shaft). [Figure 2] FIG. 2 is a perspective view of the grinding apparatus according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the grinding apparatus according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the injection unit of the grinding apparatus according to the embodiment (a view showing a cross-section perpendicular to the grinding wheel shaft). [Figure 5] FIG. 5 is a perspective view of the injection unit of the grinding apparatus according to the embodiment (for half of the injection unit, a cross-sectional view (a view showing a cross-section perpendicular to the grinding wheel shaft)). [Figure 6] FIG. 6 is a perspective view of the grinding wheel with a shaft of the grinding apparatus according to the embodiment. [Figure 7] FIG. 7 is a side view of the grinding wheel with a shaft of the grinding apparatus according to the embodiment (a view seen from a direction perpendicular to the grinding wheel shaft). [Figure 8] FIG. 8 is a cross-sectional view showing details of the injection unit and the grinding wheel with a shaft of the grinding apparatus according to the embodiment. [Figure 9] FIG. 9 is a perspective view of the grinding apparatus according to the modified example. [Figure 10] FIG. 10 is a cross-sectional view of the grinding apparatus according to Comparative Example 1. [Figure 11] FIG. 11 is a cross-sectional view of the grinding apparatus according to Comparative Example 2.

Best Mode for Carrying Out the Invention

[0019] (Embodiment) 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 without departing from the technical idea of the present disclosure. Since each drawing is for conceptually explaining the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for easy understanding. The specific numerical values of various parameters described in the following embodiments are merely examples and are not limited thereto.

[0020] <Grinding device> As shown in FIGS. 1 to FIG. 7, a grinding device (100) mainly includes a shaft-mounted grinding wheel (10) for performing internal diameter grinding of a workpiece (1), a wheel head (20) for rotating the shaft-mounted grinding wheel (10), an injection unit (21) for injecting grinding fluid, and a grinding fluid supply unit (30) for supplying grinding fluid to the injection unit (21).

[0021] The shaft-mounted grinding wheel (10) includes a metal base alloy (11), an elongated grinding wheel shaft (12) having one end supported by the base alloy (11), and a grinding wheel (13) detachably attached to the grinding wheel shaft (12). The base alloy (11) has, for example, a frustum-shaped portion (15) provided with a grinding wheel shaft (12) at the top and a cylindrical portion (16) connected to the bottom of the frustum-shaped portion (15) (see FIG. 7). 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 formed of the same material as the base alloy (11). When it is desired to increase the rigidity of the grinding wheel shaft (12), a grinding wheel shaft (12) made of a cemented carbide material may be inserted and joined to the base alloy (11). The grinding wheel (13) may have, for example, a cylindrical shape and be fixed to the grinding wheel shaft (12) with the grinding wheel shaft (12) inserted into the cylindrical hole of the grinding wheel (13). The grinding wheel (13) rotates together with the grinding wheel shaft (12) to perform internal diameter grinding of the workpiece (1). The diameter of the grinding wheel (13) is about several millimeters smaller than the diameter of the hole formed in the workpiece (1).

[0022] The base plate (11) of the mounted grinding wheel (10) has a fixing member (14) on the opposite side of the grinding wheel shaft (12) for attaching the mounted grinding wheel (10) to the 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 to allow the mounted grinding wheel (10) to move forward and backward in the axial direction of the grinding wheel shaft (12).

[0023] The injection unit (21) is positioned to cover at least a portion of the outer circumferential surface of the base plate (11). The injection unit (21) is supported by a support member (21a) on the outer wall (non-rotating portion) of the wheel head (20), and does not rotate even when the base plate (11) rotates. The injection unit (21) is formed in an annular shape when viewed from the axial direction of the grinding wheel shaft (12), and an opening (21b) is provided in the center of the injection unit (21) into which at least the top of the base plate (11) is inserted. An injection hole (22) is provided on the end face of the injection unit (21) on the grinding wheel (13) side, which discharges grinding fluid to the grinding area of ​​the workpiece (1). Multiple injection holes (22) are provided so as to surround the opening (21b) of the injection unit (21). By providing multiple injection holes (22), a sufficient flow rate of grinding fluid can be secured to supply the grinding area of ​​the workpiece (1).

[0024] An inlet hole (23) is formed on the outer circumference of the injection unit (21) for connection to the grinding fluid supply unit (30). An annular connection hole (24) is formed on the inner circumference of the injection unit (21) (the part adjacent to the opening (21b)). The connection hole (24) is connected to the injection hole (22) and the inlet hole (23), respectively. As a result, the grinding fluid supplied from the grinding fluid supply unit (30) to the injection unit (21) is supplied to the grinding area of ​​the workpiece (1) from the injection hole (22) via the inlet hole (23) and the connection hole (24). The piping from the grinding fluid supply unit (30) to the inlet hole (23) of the injection unit (21) may be arranged along the outer wall (non-rotating part) of the wheel head (20).

[0025] In the grinding apparatus (100), the grinding wheel (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 workbench. Instead of a configuration in which the mounted grinding wheel (10) is moved forward or backward in the axial direction of the grinding wheel shaft (12) together with the wheel head (20), or in addition to the said configuration, the workpiece (1) may be moved forward or backward in the axial direction of the grinding wheel shaft (12) together with the workbench that holds the workpiece (1).

[0026] <Injection Unit> In internal diameter grinding of a workpiece (1), the inner surface of the workpiece (1) is ground by inserting a grinding wheel (13) into a recess (machining hole) provided in the workpiece (1) and rotating the grinding wheel (13). The grinding wheel (13) inserted into the machining hole of 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 makes it possible to machine the inner surface of the machining hole into a desired shape.

[0027] In the grinding method of this embodiment, when grinding the inner diameter of the workpiece (1), the grinding wheel (13) is moved in the axial direction of the grinding wheel spindle (12), so the distance between the base plate (11) and the workpiece (1) (the end face of the workpiece (1) on the base plate (11) side) changes. In this embodiment, a mounted grinding wheel (10) with a short grinding wheel spindle (12) is used so that the distance between the base plate (11) and the workpiece (1) is 5 mm or less when the grinding wheel (13) grinds the deepest part of the machined hole in the workpiece (1) while avoiding contact between the base plate (11) and the workpiece (1). Therefore, the injection unit (21) for spraying grinding fluid is installed so as to cover the outer surface of the base metal (11) of the mounted grinding wheel (10), and the injection unit (21) is provided with injection holes (22) so that the grinding fluid released from the injection unit (21) is supplied to the grinding area of ​​the workpiece (1).

[0028] By attaching the injection unit (21) so as to cover at least the outer circumferential surface near the top of the base metal (11), multiple injection holes (22) can be arranged circumferentially near the grinding wheel spindle (12) (see Figure 2). This makes it possible to directly inject grinding fluid from the injection unit (21) onto the grinding area inside the machining hole of the workpiece (1).

[0029] As shown in Figure 8, the grinding fluid discharged from the injection holes (22) needs to be supplied to the grinding area through the narrow gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel spindle (12). For this reason, the opening diameter of the injection holes (22) is set to a small diameter of about 2 mm or less, preferably about 1 mm or less. In addition, the distance between the injection holes (22) and the grinding wheel spindle (12) is reduced by positioning the injection holes (22) in a vicinity of about 3 mm from the outer circumferential surface of the base metal (11). Furthermore, by providing multiple injection holes (22), even if the injection holes (22) are small in diameter, a sufficient flow rate of grinding fluid can be ensured to supply the grinding area of ​​the workpiece (1).

[0030] Furthermore, as shown in Figure 8, the injection hole (22) is drilled so that the extension of the center line C of the injection hole (22) strikes the outer surface of the grinding wheel (13) so that the grinding fluid discharged from the injection hole (22) does not bounce off the workpiece (1) and the end faces of the grinding wheel (13) on the base metal (11) side. Specifically, the inclination angle α of the extension line C with respect to the grinding wheel axis (12) (the central axis J of the grinding wheel axis (12)) is set to 20 degrees or less. In addition, the length of the injection hole (22) (the distance from the connection point with the connecting hole (24) to the opening on the grinding wheel (13) side) is made larger than the opening diameter of the injection hole (22) so that the grinding fluid is discharged from the injection hole (22) along the extension line C.

[0031] Furthermore, the end face of the injection unit (21) on the grinding wheel (13) side is either flush with the end face of the base metal (11) on the grinding wheel (13) side, or positioned further away from the grinding wheel (13) than the end face of the base metal (11) on the grinding wheel (13) side. Conversely, if the injection unit (21) is positioned closer to the grinding wheel (13) than the end face of the base metal (11) on the grinding wheel (13) side, the grinding wheel spindle (12) (specifically the part between the base metal (11) and the grinding wheel (13)) would need to be lengthened to prevent contact between the injection unit (21) and the workpiece (1). This would reduce the rigidity of the grinding wheel spindle (12).

[0032] <Mounted grinding wheel> As described above, in order to reduce the distance between the injection hole (22) of the injection unit (21) and the grinding wheel shaft (12), and to make the inclination angle α of the center line (extension line C) of the injection hole (22) with respect to the grinding wheel shaft (12) (central axis J) 20 degrees or less, the mounted grinding wheel (10) may be configured as follows.

[0033] As shown in Figure 7, the base metal (11) of the mounted grinding wheel (10) may have a frustoconical portion (15) with a grinding wheel shaft (12) at its apex. The inclination angle θ of the outer surface of the frustoconical portion (15) with respect to the grinding wheel shaft (12) (central axis J) at the apex of the frustoconical portion (15) is between 0° and approximately 20°. Also, the step difference between the outer surface of the frustoconical portion (15) and the outer surface of the grinding wheel shaft (12) at the apex of the frustoconical portion (15) is approximately 5 mm or less.

[0034] By the way, if the inclination angle θ of the entire outer surface of the frustoconical portion (15) is to be 20° or less, the rigidity of the frustoconical portion (15), i.e., the base metal (11), will decrease. Therefore, in order to secure space for installing the injection unit (21) so that the injection hole (22) (extension line C) faces the direction of the grinding area of ​​the workpiece (1), a concave surface (15a) may be provided on the outer surface of the frustoconical portion (15) of the base metal (11), as shown in Figure 7. This makes it easier to drill the injection hole (22) in the desired direction while suppressing adverse effects on the rigidity of the base metal (11), i.e., the mounted grinding wheel (10). For example, the inclination angle θ of the concave surface (15a) of the frustoconical portion (15) with respect to the grinding wheel axis (12) (central axis J) is 0° or more and 20° or less at the top of the frustoconical portion (15), the inclination angle θ increases from the top to the bottom of the frustoconical portion (15), and at the bottom of the frustoconical portion (15), the concave surface (15a) may be connected to the outer 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) at the bottom of the frustoconical portion (15) with respect to the central axis J of the grinding wheel axis (12).

[0035] The shape of the base plate (11) is a combination of a frustoconical portion (15) having an outer 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. However, in the example shown in Figure 7, the outer surface of the frustoconical portion (15) is replaced with a curved concave surface (15a). As shown in Figure 7, when viewing the mounted grinding wheel (10) from a direction perpendicular to the grinding wheel shaft (12), a curve (for example, a parabola or circular arc) with an inclination angle θ of 0 to 20° with respect to the grinding wheel shaft (12) begins to extend from the top of the frustoconical portion (15), which has a diameter slightly larger (for example, about 1 to 2 mm) than the diameter of the grinding wheel (13), and the inclination angle θ changes significantly towards the bottom of the frustoconical portion (15). The curve is connected to the outer surface of the cylindrical part (16), which has a larger diameter than the grinding wheel (13), at an angle φ of 40° to 90°.

[0036] In the shape of the base metal (11) shown in Figure 7, the rigidity of the base metal (11) is slightly reduced compared to the case where the outer surface of the frustoconical portion (15) is not concave (15a). However, this reduction in rigidity of the base metal (11) is small enough that it does not pose a problem compared to the effect of improving rigidity by shortening the grinding wheel shaft (11).

[0037] Note that the configuration of the mounted grinding wheel (10) shown in Figure 7 is illustrative, and as long as the inclination angle θ of the outer surface of the frustoconical portion (15) with respect to the grinding wheel axis (12) (central axis J) at the top of the frustoconical portion (15) (the end on the grinding wheel (13) side) is between 0° and approximately 20°, the injection holes (22) can be drilled in the desired direction even if the entire outer surface of the frustoconical portion (15) is not made concave (15a). Specifically, only the outer surface near the top of the frustoconical portion (15) may be made concave. Alternatively, the outer surface of the frustoconical portion (15) may be composed of multiple flat slopes with different inclination angles, and only the flat slopes near the top of the frustoconical portion (15) may have an inclination angle of between 0° and approximately 20°.

[0038] <Position of injection holes> In order to ensure that the grinding fluid released from the injection hole (22) of the injection unit (21) strikes the outer surface of the grinding wheel (13), the injection unit (21) and the mounted grinding wheel (11) illustrated in Figure 8 may be configured as follows.

[0039] The minimum distance L1 between the base metal (11) and the workpiece (1) during grinding is 5 mm or less, for example, 4 mm. The distance L2 between the end face of the base metal (11) on the grinding wheel (13) side and the end face of the grinding wheel (13) on the base metal (11) side (axial length of the grinding wheel spindle (12) in the portion where the grinding wheel (13) is not provided) is for example, 7.5 mm. The opening diameter of the injection hole (22) is about 2 mm or less, for example, 1 mm. The inclination angle α of the center line (extension line C) of the injection hole (22) with respect to the grinding wheel spindle (12) (central axis J) is 20 degrees or less, for example, 16 degrees. The radius D2 of the top of the base metal (11) is about 1 to 3 mm larger than the radius D1 of the grinding wheel (13), for example, D1 is 5.75 mm and D2 is 7 mm.

[0040] In the above configuration, the distance L3 between the opening center position of the injection hole (22) and the grinding wheel spindle (12) (central axis J) is set to be greater than "D1 + L2 × tan(α)" (7.85 mm in this example), for example, 8.21 mm. The reason for this is that if L3 is less than "D1 + L2 × tan(α)", the grinding fluid discharged from the injection hole (22) will not reach the outer surface of the grinding wheel (13).

[0041] In the embodiment shown in Figure 2, etc., the injection unit (21) is arranged to surround the entire outer circumference of the base plate (11) (frustoconical portion (15)) of the mounted grinding wheel (10). This makes it easy to increase the number of injection holes (22).

[0042] On the other hand, in the modified example shown in Figure 9, the injection unit (21) is configured, for example, in a semicircular or U-shape so as to easily remove the injection unit (21) and the like, to surround a part of the outer circumference (about half a circumference in this example) of the base metal (11) (frustoconical portion (15)). If the grinding fluid supply unit (30) is composed of flexible piping separate from the wheel head (20), the injection unit (21) may be removed together with the piping.

[0043] <Features of the embodiment (including modified examples)> The grinding method of this embodiment is a grinding method that grinds the inner diameter of a workpiece (1) by rotating a grinding wheel (13) attached to a grinding wheel shaft (12) protruding from a base metal (11). 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). Grinding fluid released from a spray unit (21) installed to cover the outer circumferential surface of the base metal (11) is supplied to the grinding area of ​​the workpiece (1).

[0044] In the grinding method of this embodiment, 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, sufficient grinding fluid can be supplied to the grinding area of ​​the workpiece (1) from the injection unit (21) covering the outer surface of the base metal (11). As a result, grinding burn can be suppressed, and wear of the grinding wheel (13) can be suppressed, extending the lifespan of the mounted grinding wheel. In addition, since the grinding wheel spindle (12) can be shortened, a decrease in processing accuracy caused by the deflection of the grinding wheel spindle (12) can be suppressed, and the time required for spark out can be shortened, thereby shortening the processing time and improving the processing speed.

[0045] The grinding apparatus (100) of this embodiment grinds the inner diameter of a workpiece (1) by rotating a grinding wheel (13) attached to a grinding wheel spindle (12) protruding from a base plate (11). The grinding apparatus (100) includes a spray unit (21) installed so as to cover the outer circumferential surface of the base plate (11). The spray unit (21) has spray holes (22) for spraying grinding fluid. The spray holes (22) are provided on the spray unit (21) so that the grinding fluid released from the spray holes (22) is supplied to the grinding area of ​​the workpiece (1).

[0046] In the grinding apparatus (100) of this embodiment, 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, sufficient grinding fluid can be supplied to the grinding area of ​​the workpiece (1) from the injection holes (22) of the injection unit (21) that covers the outer surface of the base metal (11). As a result, grinding burn can be suppressed, and wear of the grinding wheel (13) can be suppressed, extending the lifespan of the mounted grinding wheel. In addition, since the grinding wheel spindle (12) can be shortened, a decrease in processing accuracy caused by the deflection of the grinding wheel spindle (12) can be suppressed, and the time required for spark out can be shortened, thereby shortening the processing time and improving the processing speed.

[0047] On the other hand, if the grinding fluid supply pipe is bent along the axial direction of the grinding wheel spindle and the nozzle of the grinding fluid supply pipe is positioned toward the machining hole, as in the conventional method, the grinding fluid nozzle (31) can be positioned toward the machining hole when the grinding wheel spindle (12) is long, as in Comparative Example 1 shown in Figure 10. However, when the grinding wheel spindle (12) is short, as in Comparative Example 2 shown in Figure 11, the grinding fluid nozzle (31) cannot be positioned toward the machining hole. Note that in Comparative Examples 1 and 2 shown in Figures 10 and 11, the same elements as in the embodiment shown in Figure 3 are denoted by the same reference numerals. As mentioned above, the grinding wheel spindle should be kept as short as possible to ensure rigidity. However, when the distance between the base plate or wheel head of the grinding wheel spindle and the workpiece is about 5 mm or less, the machining hole in the workpiece is blocked by the base plate or wheel head, as in Comparative Example 2 shown in Figure 11, making it impossible to properly position the grinding fluid nozzle. This can result in insufficient supply of grinding fluid to the grinding area of ​​the workpiece, leading to problems such as grinding burn where the temperature of the grinding area reaches over 500°C, and a shortened lifespan of the grinding wheel.

[0048] In the grinding apparatus (100) of this embodiment, a plurality of small-diameter injection holes (22) of 2 mm or less may be arranged near the outer circumferential surface of the base metal (11). This makes it easier for the grinding fluid released from the injection holes (22) to enter the gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel spindle (12), thereby facilitating the supply of grinding fluid to the grinding area of ​​the workpiece (1). In this case, the inclination angle α of the center line (extension line C) of each injection hole (22) with respect to the grinding wheel spindle (12) (center axis J) is 20 degrees or less, and each injection hole (22) may be drilled so that the extension line C contacts the outer circumferential surface of the grinding wheel (13). In this way, grinding fluid can be efficiently supplied to the grinding area of ​​the workpiece (1) from the gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel spindle (12).

[0049] In the grinding apparatus (100) of the embodiment, the base metal (11) has a frustoconical portion (15) with a grinding wheel spindle (12) at its apex, and the inclination angle θ of the outer surface of the frustoconical portion (15) with respect to the grinding wheel spindle (12) at the apex of the frustoconical portion (15) may be 0° or more and 20° or less. This makes it easy to provide injection holes (22) in the injection unit (21) covering the outer surface of the frustoconical portion (15) in the direction of the grinding area of ​​the workpiece (1).

[0050] (Other embodiments) Although embodiments and modifications have been described above, it will be understood that various changes 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. [Industrial applicability]

[0051] As described above, this disclosure is useful for grinding methods and grinding apparatus. [Explanation of symbols]

[0052] 1 Workpiece 11 base money 12 Grinding wheel shaft 13 Sharpening stones 15. Truncated cone section 21 Injection Unit 22 Injection hole 100 Grinding device

Claims

1. A grinding method for grinding the inner diameter of a workpiece (1) by rotating a grinding wheel (13) attached to a grinding wheel shaft (12) protruding from a base metal (11), The distance between the base metal (11) and the workpiece (1) changes during grinding, and the distance when grinding the innermost part of the workpiece (1) is 5 mm or less. Grinding fluid discharged from the injection unit (21), which is installed to cover the outer surface of the base metal (11), is supplied to the grinding area of ​​the workpiece (1). The injection unit (21) is provided with injection holes (22) within 3 mm from the outer circumferential surface of the base metal (11). The grinding fluid released from the injection hole (22) is supplied from the gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel spindle (12) toward the grinding area of ​​the workpiece (1). Grinding method.

2. A grinding device that performs internal diameter grinding of a workpiece (1) by rotating a grinding wheel (13) attached to a grinding wheel shaft (12) protruding from a base metal (11), The base metal (11) is provided with a spray unit (21) that is installed to cover the outer circumferential surface and sprays grinding fluid, The injection unit (21) is provided with injection holes (22) so that the grinding fluid discharged from the injection unit (21) is supplied to the grinding area of ​​the workpiece (1). The injection holes (22) are located within 3 mm of the outer circumferential surface of the base metal (11). The grinding fluid released from the injection hole (22) is supplied from the gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel spindle (12) toward the grinding area of ​​the workpiece (1). Grinding device.

3. In the grinding apparatus of claim 2, The injection holes (22) consist of a plurality of small holes (22) with a diameter of 2 mm or less, arranged near the outer circumferential surface of the base metal (11). Grinding device.

4. In the grinding apparatus of claim 3, The inclination angle α of the centerlines of the plurality of holes (22) with respect to the grinding wheel axis (12) is 20 degrees or less. The plurality of holes (22) are drilled such that the extension of the center line strikes the outer surface of the grinding wheel (13). Grinding device.

5. In a grinding apparatus according to any one of claims 2 to 4, The base metal (11) has a frustoconical portion (15) at its top on which the grinding wheel shaft (12) is provided. At the apex of the frustum portion (15), the inclination angle θ of the outer surface of the frustum portion (15) with respect to the grinding wheel shaft (12) is 0° or more and 20° or less. Grinding device.

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