Grinding method and grinding device

Abstract

A grinding device (100) rotates a grindstone (13) attached to a grindstone shaft (12) protruding from a base metal (11) to perform inner-diameter grinding of a workpiece (1). A spout unit (21) for spouting a grinding liquid is installed to cover the outer circumferential surface of the base metal (11). A spout hole (22) is provided to the spout unit (21) so as to supply the grinding liquid emitted from the spout unit (21) to a grinding spot of the workpiece (1).

Description

Grinding method and grinding device

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

[0002] BACKGROUND ART Conventionally, grinding devices for grinding the inner diameter of workpieces have used a mounted grinding wheel in which a grinding wheel is attached to a grinding wheel 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 grinding device that can shorten the grinding wheel spindle to ensure the rigidity of the grinding wheel spindle 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), in which 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 an injection unit (21) installed so as to cover the outer peripheral surface of the base metal (11) is supplied to the grinding point of the workpiece (1).

[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 injection unit (21) covering the outer peripheral surface of the base metal (11) can sufficiently supply 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] The second aspect is a grinding device that rotates a grinding wheel (13) attached to a grinding wheel spindle (12) protruding from a base metal (11) to grind the internal diameter of a workpiece (1), and is equipped with an injection unit (21) that is installed to cover the outer peripheral surface of the base metal (11) and injects grinding fluid, and an injection hole (22) is provided in the injection unit (21) so that the grinding fluid released from the injection unit (21) is supplied to the grinding point of the workpiece (1).

[0011] In the second aspect, 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 injection holes (22) of the injection unit (21) covering the outer peripheral surface of the base metal (11) can sufficiently supply 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.

[0012] In a third aspect, in the second aspect, a plurality of small holes (22) having a diameter of 2 mm or less are arranged in the vicinity of the outer circumferential surface of the base metal (11).

[0013] In the third aspect, since a plurality of small-diameter holes (22) are arranged near the outer peripheral 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 machining hole in the workpiece (1) and the grinding wheel shaft (12), making it easy to supply the grinding fluid to the grinding point of the workpiece (1).

[0014] In the fourth aspect, in the third aspect, the inclination angle α of the center lines of the plurality of holes (22) relative to the grinding wheel shaft (12) is 20 degrees or less, and the plurality of holes (22) are drilled so that the extension of the center lines abuts on the outer peripheral surface of the grinding wheel (13).

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

[0016] In a fifth aspect, in any one of the second to fourth aspects, the base metal (11) has a truncated cone portion (15) with the grinding wheel shaft (12) provided at its apex, and the inclination angle θ of the outer peripheral surface of the truncated cone portion (15) with respect to the grinding wheel shaft (12) at the apex of the truncated cone portion (15) is equal to or greater than 0° and equal to or less than 20°.

[0017] In the fifth aspect, it becomes easy to provide the injection holes (22) in the injection unit (21) covering the outer peripheral surface of the truncated cone portion (15) so as to face the grinding portion of the workpiece (1).

[0018] FIG. 1 is a side view (viewed from a direction perpendicular to the grinding wheel spindle) of a grinding device according to an embodiment. FIG. 2 is a perspective view of a grinding device according to an embodiment. FIG. 3 is a cross-sectional view of a grinding device according to an embodiment. FIG. 4 is a cross-sectional view of an injection unit of a grinding device according to an embodiment (view showing a cross-section perpendicular to the grinding wheel spindle). FIG. 5 is a perspective view of an injection unit of a grinding device according to an embodiment (a cross-sectional view of half of the injection unit (view showing a cross-section perpendicular to the grinding wheel spindle)). FIG. 6 is a perspective view of a mounted grindstone of a grinding device according to an embodiment. FIG. 7 is a side view (viewed from a direction perpendicular to the grinding wheel spindle) of a mounted grindstone of a grinding device according to an embodiment. FIG. 8 is a cross-sectional view showing details of the injection unit and mounted grindstone of a grinding device according to an embodiment. FIG. 9 is a perspective view of a grinding device according to a modified example. FIG. 10 is a cross-sectional view of a grinding device according to Comparative Example 1. FIG. 11 is a cross-sectional view of a grinding device according to Comparative Example 2.

[0019] (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.

[0020] <Grinding Device> As shown in Figures 1 to 7, the grinding device (100) mainly includes a grinding wheel (10) that grinds the internal diameter of the workpiece (1), a wheel head (20) that rotates the grinding wheel (10), an injection unit (21) that injects grinding fluid, and a grinding fluid supply section (30) that supplies grinding fluid to the injection unit (21).

[0021] 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) (see FIG. 7). The cylindrical portion (16) may be chamfered to accommodate 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). To increase the rigidity of the grinding wheel stalk (12), 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.

[0022] 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).

[0023] The injection unit (21) is disposed so as to cover at least a portion of the outer peripheral surface of the base metal (11). The injection unit (21) is supported on the outer wall (non-rotating portion) of the wheel head (20) via a support member (21a), and does not rotate even when the base metal (11) rotates. The injection unit (21) is formed in an annular shape when viewed from the axial direction of the grinding wheel spindle (12). An opening (21b) is provided in the center of the injection unit (21) into which at least the top of the base metal (11) is inserted. An injection hole (22) is provided in the end face of the injection unit (21) facing the grinding wheel (13) to discharge grinding fluid to the grinding location of the workpiece (1). A plurality of injection holes (22) are provided so as to surround the opening (21b) of the injection unit (21). By providing a plurality of injection holes (22), a sufficient flow rate of grinding fluid can be ensured to be supplied to the grinding location of the workpiece (1).

[0024] An introduction hole (23) connected to the grinding fluid supply unit (30) is formed in the outer periphery of the spray unit (21). An annular connection hole (24) is formed in the inner periphery of the spray unit (21) (the portion adjacent to the opening (21b)). The connection hole (24) is connected to the spray hole (22) and the introduction hole (23). As a result, the grinding fluid supplied from the grinding fluid supply unit (30) to the spray unit (21) passes through the introduction hole (23) and the connection hole (24) and is then supplied to the grinding point of the workpiece (1). The piping from the grinding fluid supply unit (30) to the introduction hole (23) of the spray unit (21) may be arranged along the outer wall (non-rotating portion) of the wheel head (20).

[0025] 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).

[0026] <Injection unit> 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.

[0027] 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 shank (12), so that the distance between the base metal (11) and the workpiece (1) (the end face of the workpiece (1) facing the base metal (11)) changes. In this embodiment, a mounted grindstone (10) with a short grindstone shank (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 machined hole in the workpiece (1) with the grindstone (13) while avoiding contact between the base metal (11) and the workpiece (1). For this reason, an injection unit (21) for injecting the grinding fluid is installed so as to cover the outer peripheral surface of the base metal (11) of the axle-mounted grinding wheel (10), and an injection hole (22) is provided in the injection unit (21) so that the grinding fluid released from the injection unit (21) is supplied to the grinding point of the workpiece (1).

[0028] By attaching the injection unit (21) so as to cover at least the outer peripheral surface near the top of the base metal (11), it is possible to arrange a plurality of injection holes (22) circumferentially near the periphery of 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 point inside the processed hole of the workpiece (1).

[0029] As shown in Figure 8, the grinding fluid discharged from the jet hole (22) must be supplied to the grinding point through the narrow gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel stalk (12). Therefore, the opening diameter of the jet hole (22) is set to a small diameter of approximately 2 mm or less, preferably approximately 1 mm or less. Furthermore, by locating the jet hole (22) within approximately 3 mm of the outer circumferential surface of the base metal (11), the distance between the jet hole (22) and the grinding wheel stalk (12) is reduced. Furthermore, by providing multiple jet holes (22), a sufficient flow rate of grinding fluid can be ensured to be supplied to the grinding point of the workpiece (1) even if the jet hole (22) has a small diameter.

[0030] 8, the ejection hole (22) is drilled so that an extension line C of the center line of the ejection hole (22) hits the outer peripheral surface of the grinding wheel (13) so that the grinding fluid ejected from the ejection hole (22) does not bounce off the end faces of the workpiece (1) and 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 shaft (12) (the central axis J of the grinding wheel shaft (12)) is set to 20 degrees or less. Furthermore, the length of the ejection hole (22) (the distance from the connection point with the connection hole (24) to the opening on the grinding wheel (13) side) is set to be greater than the opening diameter of the ejection hole (22) so that the grinding fluid is ejected from the ejection hole (22) along the extension line C.

[0031] 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 is located farther 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 located closer to the grinding wheel (13) than the end face of the base metal (11) on the grinding wheel (13) side, it is necessary to lengthen the grinding wheel spindle (12) (specifically, the portion between the base metal (11) and the grinding wheel (13)) to prevent contact between the injection unit (21) and the workpiece (1). This reduces the rigidity of the grinding wheel spindle (12).

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

[0033] As shown in Figure 7, the base metal (11) of the mounted grindstone (10) may have a truncated cone portion (15) with a grindstone shaft (12) attached to its apex. At the apex of the truncated cone portion (15), the outer peripheral surface of the truncated cone portion (15) is inclined at an angle θ of approximately 0° to 20° with respect to the grindstone shaft (12) (central axis J). At the apex of the truncated cone portion (15), the step between the outer peripheral surface of the truncated cone portion (15) and the outer peripheral surface of the grindstone shaft (12) is approximately 5 mm or less.

[0034] However, if the inclination angle θ of the entire outer peripheral surface of the truncated cone portion 15 is set to 20° or less, the rigidity of the truncated cone portion 15, i.e., the base metal 11, will decrease. Therefore, in order to ensure space for installing the injection unit 21 so that the injection hole 22 (extension line C) faces the grinding point of the workpiece 1, a concave surface 15a may be formed on the outer peripheral surface of the truncated cone 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 minimizing adverse effects on the rigidity of the base metal 11, i.e., the mounted grindstone 10. For example, the inclination angle θ of the concave surface 15a of the truncated cone portion 15 with respect to the grinding wheel spindle 12 (central axis J) may be between 0° and 20° at the top of the truncated cone portion 15, and the inclination angle θ may increase from the top to the bottom of the truncated cone portion 15, so that 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 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.

[0035] 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 Fig. 7, the outer peripheral surface of the truncated cone portion (15) is replaced with a curved concave surface (15a). As shown in Fig. 7, 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°.

[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 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.

[0037] Note that the configuration of the mounted grindstone (10) shown in Figure 7 is an example. As long as the inclination angle θ of the outer peripheral surface of the truncated cone portion (15) with respect to the grindstone shaft (12) (central axis J) at the apex (end portion of the grindstone (13) side) of the truncated cone portion (15) is between 0° and approximately 20°, the injection holes (22) can be drilled in the desired direction even if the entire outer peripheral surface of the truncated cone portion (15) is not made concave (15a). Specifically, only the outer peripheral surface near the apex of the truncated cone portion (15) may be made concave. Alternatively, the outer peripheral surface of the truncated cone portion (15) may be made up of a plurality of flat slopes with different inclination angles, and only the flat slopes near the apex of the truncated cone portion (15) may have an inclination angle of between 0° and approximately 20°.

[0038] <Position of injection hole> In order to ensure that the grinding fluid released from the injection hole (22) of the injection unit (21) hits the outer peripheral surface of the grinding wheel (13), the injection unit (21) and the shaft-mounted grinding wheel (11) illustrated in FIG. 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) facing the grinding wheel (13) and the end face of the grinding wheel (13) facing the base metal (11) (the axial length of the grinding wheel shaft (12) where the grinding wheel (13) is not provided) is, for example, 7.5 mm. The opening diameter of the injection hole (22) is approximately 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 shaft (12) (center axis J) is 20 degrees or less, for example, 16 degrees. Compared to the radius D1 of the grinding wheel (13), the radius D2 of the top of the base metal (11) is approximately 1 to 3 mm larger; for example, D1 is 5.75 mm and D2 is 7 mm.

[0040] In the above configuration, the distance L3 between the center position of the opening of the ejection hole (22) and the grinding wheel shaft (12) (center axis J) is set to be larger 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 smaller than "D1 + L2 × tan(α)", the grinding fluid ejected from the ejection hole (22) will not reach the outer peripheral surface of the grinding wheel (13).

[0041] <Modification of Injection Unit> In the embodiment shown in Fig. 2 etc., the injection unit (21) is arranged to surround the entire outer periphery of the base metal (11) (frustum portion (15)) of the mounted grindstone (10). This makes it easy to increase the number of injection holes (22) arranged.

[0042] 9, the injection unit (21) is configured, for example, in a semicircular or U-shape so as to surround a part (about half the circumference in this example) of the outer periphery of the base metal (11) (frustum cone portion (15)) in order to facilitate removal of the injection unit (21). When the grinding fluid supply unit (30) is configured from 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 variations)> 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. Grinding fluid is released from an injection unit (21) installed so as to cover the outer peripheral surface of the base metal (11) and supplied to the grinding point of the workpiece (1).

[0044] 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 spray unit (21) covering the outer peripheral surface of the base metal (11) can sufficiently supply grinding fluid to the grinding point 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, since 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.

[0045] The grinding device (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 metal (11). The grinding device (100) includes an injection unit (21) installed to cover the outer peripheral surface of the base metal (11). The injection unit (21) has an injection hole (22) for injecting a grinding fluid. The injection hole (22) is provided in the injection unit (21) so that the grinding fluid released from the injection hole (22) is supplied to the grinding location of the workpiece (1).

[0046] In the grinding device (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, the injection holes (22) of the injection unit (21) covering the outer peripheral surface of the base metal (11) can sufficiently supply grinding fluid to the grinding point 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, since 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) and shorten the time required for spark-out, thereby shortening the processing time, i.e., improving the processing speed.

[0047] On the other hand, when 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 machined hole as in the conventional case, if the grinding wheel spindle (12) is long as in Comparative Example 1 shown in Fig. 10, 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. 11, the grinding fluid nozzle (31) cannot be positioned toward the machined hole. Note that in Comparative Examples 1 and 2 shown in Figs. 10 and 11, the same elements as in the embodiment shown in Fig. 3 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.

[0048] In the grinding device (100) of this embodiment, the injection holes (22) may be a plurality of small injection holes (22) with a diameter of 2 mm or less, arranged near the outer circumferential surface of the base metal (11). This allows the grinding fluid released from the injection holes (22) to easily enter the gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel shaft (12), thereby facilitating the supply of grinding fluid to the grinding point 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 shaft (12) (center axis J) may be 20 degrees or less, and each injection hole (22) may be drilled so that the extension line C hits the outer circumferential surface of the grinding wheel (13). This allows the grinding fluid to be efficiently supplied to the grinding point of the workpiece (1) through the gap between the inner wall surface of the machining hole in the workpiece (1) and the grinding wheel shaft (12).

[0049] In the grinding device (100) of the embodiment, the base metal (11) has a truncated cone portion (15) with a grinding wheel shaft (12) attached to its apex, and the inclination angle θ of the outer peripheral surface of the truncated cone portion (15) with respect to the grinding wheel shaft (12) at the apex of the truncated cone portion (15) may be between 0° and 20°. This makes it easy to provide an injection hole (22) in the injection unit (21) covering the outer peripheral surface of the truncated cone portion (15) facing the grinding location of the workpiece (1).

[0050] While the 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.

[0051] As described above, the present disclosure is useful for a grinding method and a grinding apparatus.

[0052] REFERENCE SIGNS LIST 1 workpiece 11 base metal 12 grinding wheel spindle 13 grinding wheel 15 truncated cone portion 21 injection unit 22 injection hole 100 grinding device

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) during grinding changes, and the distance is 5 mm or less when grinding the innermost part of the workpiece (1), and grinding fluid is sprayed from a spray unit (21) installed so as to cover the outer circumferential surface of the base metal (11) and supplied to the grinding point of the workpiece (1).

2. A grinding device 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), comprising an injection unit (21) that is installed so as to cover the outer peripheral surface of the base metal (11) and that injects grinding fluid, and an injection hole (22) is provided in the injection unit (21) so that the grinding fluid released from the injection unit (21) is supplied to a grinding point of the workpiece (1).

3. A grinding device according to claim 2, wherein the injection holes (22) are a plurality of small holes (22) having a diameter of 2 mm or less, and are arranged in the vicinity of the outer circumferential surface of the base metal (11).

4. A grinding device according to claim 3, wherein the inclination angle α of the center lines of the plurality of holes (22) relative to the grindstone shaft (12) is 20 degrees or less, and the plurality of holes (22) are drilled so that an extension of the center lines abuts on the outer circumferential surface of the grindstone (13).

5. A grinding device according to any one of claims 2 to 4, wherein the base metal (11) has a conical frustum portion (15) with the grindstone shaft (12) attached at its apex, and the inclination angle θ of the outer circumferential surface of the conical frustum portion (15) at the apex of the conical frustum portion (15) relative to the grindstone shaft (12) is equal to or greater than 0° and equal to or less than 20°.

Images