Grinding method and grinding device

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 technology]

[0002] 2. Description of the Related Art Conventionally, grinding devices for performing internal grinding of workpieces have used a grinding wheel with a shaft, in which a grinding wheel is attached to a grinding wheel shaft that is rotated by a wheel head (see Patent Document 1).

[0003] In internal grinding, the grinding load is applied to the grinding wheel, which causes the grinding wheel spindle to bend. This bending is significant compared to the processing accuracy required for grinding, so for high-precision internal grinding, it is necessary to perform a spark-out, which stops the axial movement of the grinding wheel spindle for several seconds until the bending disappears. If the machining hole is long and narrow, the grinding wheel spindle to be used must also be long and narrow. In that case, the rigidity of the grinding wheel spindle decreases, and it takes time to spark-out to recover the bending of the grinding wheel spindle, which increases the processing time.

[0004] In addition, in internal grinding, it is necessary to supply the grinding fluid to the grinding point of the workpiece. When machining a small diameter long and narrow hole, it is necessary to arrange 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 to follow the axial direction of the grinding wheel spindle and arranging the grinding fluid nozzle toward the machined hole. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-69303 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, if you try to shorten the grinding wheel shaft 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 machining hole, making it difficult to properly position the injection port of the grinding fluid. If the grinding fluid cannot be supplied sufficiently to the grinding point, problems such as grinding burn, where the temperature of the grinding point reaches 500°C or more, or shortening the life of the grinding wheel will occur.

[0007] An object of the present disclosure is to provide a grinding method and grinding apparatus that can shorten the grinding wheel spindle to ensure the rigidity of the grinding wheel spindle while supplying a sufficient amount of grinding fluid to the grinding point of the workpiece. [Means for solving the problem]

[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) during grinding changes, and the distance is 5 mm or less when grinding the innermost part of the workpiece (1), 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 embodiment, even if the grindstone shaft (12) is shortened so that the distance between the base metal (11) and the workpiece (1) during grinding is 5 mm or less, the injection unit (21) covering the outer circumferential surface of the base metal (11) can supply sufficient grinding fluid to the grinding point of the workpiece (1). This makes it possible to suppress grinding burn and wear of the grindstone (13), thereby extending the life of the grindstone with shaft.

[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 embodiment, even if the grindstone shaft (12) is shortened so that the distance between the base metal (11) and the workpiece (1) during grinding is 5 mm or less, the grinding fluid can be sufficiently supplied to the grinding point of the workpiece (1) from the injection holes (22) of the injection unit (21) covering the outer circumferential surface of the base metal (11). This makes it possible to suppress grinding burn and to suppress wear of the grindstone (13), thereby extending the life of the grindstone with shaft.

[0012] In the third embodiment, in the second embodiment, 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 discharged from each hole (22) easily penetrates into the gap between the inner wall surface of the machined 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) with respect to the grinding wheel 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 peripheral surface of the grinding wheel (13).

[0015] In the fourth aspect, the grinding fluid can be efficiently supplied to the grinding location of the workpiece (1) through the gap between the inner wall surface of the machined hole in the workpiece (1) and the grindstone shaft (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 grindstone shaft (12) provided at its apex, and the inclination angle θ of the outer circumferential surface of the truncated cone portion (15) with respect to the grindstone 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 circumferential surface of the truncated cone portion (15) so as to face the grinding portion of the workpiece (1). [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a side view of a grinding device according to an embodiment (as viewed from a direction perpendicular to a grinding wheel axis). [Diagram 2] FIG. 2 is a perspective view of the grinding device according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view of the grinding device according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the injection unit of the grinding device according to the embodiment (a cross-sectional view perpendicular to the grinding wheel axis). [Diagram 5] FIG. 5 is a perspective view of the injection unit of the grinding device according to the embodiment (a cross-sectional view of half of the injection unit (a view showing a cross section perpendicular to the grindstone axis)). [Figure 6] FIG. 6 is a perspective view of a mounted grindstone of the grinding device according to the embodiment. [Figure 7] FIG. 7 is a side view of the mounted grindstone of the grinding device according to the embodiment (as viewed from a direction perpendicular to the grindstone axis). [Figure 8] FIG. 8 is a cross-sectional view showing details of the injection unit and the mounted grindstone of the grinding machine according to the embodiment. [Figure 9] FIG. 9 is a perspective view of a grinding device according to a modified example. [Figure 10] FIG. 10 is a cross-sectional view of the grinding device according to the first comparative example. [Figure 11] FIG. 11 is a cross-sectional view of the grinding device according to the second comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] (Embodiment) Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical idea of ​​the present disclosure. Since each drawing is intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding. The specific numerical values ​​of various parameters described in the following embodiments are merely examples and are not limited thereto.

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

[0021] The grindstone (10) includes a metal base (11), an elongated grindstone shaft (12) one end of which is supported by the base (11), and a grindstone (13) replaceably attached to the grindstone shaft (12). The base (11) has, for example, a conical truncated portion (15) on the top of which the grindstone shaft (12) is provided, and a cylindrical portion (16) connected to the bottom of the conical truncated portion (15) (see FIG. 7). The cylindrical portion (16) may be chamfered for a wrench so as to be attached to the wheel head (20). The grindstone shaft (12) may be integrally molded from the same material as the base (11). If it is desired to increase the rigidity of the grindstone shaft (12), the grindstone shaft (12) made of a super-hard material may be inserted and joined to the base (11). The grindstone 13 may have, for example, a cylindrical shape and be fixed to the grindstone spindle 12 with the grindstone spindle 12 inserted into a cylindrical hole in the grindstone 13. The grindstone 13 rotates together with the grindstone spindle 12 to grind the inner diameter of the workpiece 1. The diameter of the grindstone 13 is several mm smaller than the diameter of the hole to be formed in the workpiece 1.

[0022] The base metal (11) of the mounted grinding wheel (10) has a fixing member (14) on the opposite side to the grinding wheel shank (12) for mounting 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 pull-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 shank (12).

[0023] The injection unit (21) is disposed so as to cover at least a part 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 the injection unit (21) 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), and an opening (21b) into which at least the top of the base metal (11) is inserted is provided in the center of the injection unit (21). An injection hole (22) is provided in the end face of the injection unit (21) on the grinding wheel (13) side, which ejects the grinding fluid to the grinding portion 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), it is possible to ensure a sufficient flow rate of the grinding fluid to be supplied to the grinding portion of the workpiece (1).

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

[0025] In the grinding device 100, the grindstone 13 may be rotated at a high speed and the workpiece 1 may be rotated at a low speed. In this case, the workpiece 1 may be held on a rotatable worktable. Instead of or in addition to the configuration in which the 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 worktable that holds the workpiece 1 in the axial direction of the grindstone spindle 12.

[0026] <Injection unit> In internal grinding of the workpiece (1), a grindstone (13) is inserted into a recess (machined hole) provided in the workpiece (1) and rotated to grind the inner surface of the machined hole. The grindstone (13) inserted into the machined hole of the workpiece (1) is movable in the axial direction of the grindstone shaft (12) and also in the radial direction of the grindstone shaft (12). This allows the inner surface of the machined hole to be machined into a desired shape.

[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 shaft (12), so that the distance between the base metal (11) and the workpiece (1) (the end face of the workpiece (1) on the base metal (11) side) changes. In this embodiment, a shaft-mounted grindstone (10) with a short grindstone shaft (12) is used so that the distance between the base metal (11) and the workpiece (1) is 5 mm or less when grinding the innermost part of the processed hole of 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) that injects 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) in a circumferential manner near the periphery of the grinding wheel spindle (12) (see FIG. 2). This makes it possible to directly inject grinding fluid from the injection unit (21) onto the grinding point inside the machined hole of the workpiece (1).

[0029] As shown in FIG. 8, the grinding fluid discharged from the ejection hole (22) needs to be supplied to the grinding point from the narrow gap between the inner wall surface of the machining hole in the workpiece (1) and the grindstone shaft (12). For this reason, the opening diameter of the ejection hole (22) is set to a small diameter of about 2 mm or less, preferably about 1 mm or less. In addition, the ejection hole (22) is arranged within about 3 mm from the outer circumferential surface of the base metal (11) to reduce the distance between the ejection hole (22) and the grindstone shaft (12). In addition, by providing multiple ejection holes (22), it is possible to ensure a sufficient flow rate of the grinding fluid to be supplied to the grinding point of the workpiece (1) even if the ejection 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 circumferential surface of the grinding wheel (13) so that the grinding fluid ejected from the ejection hole (22) does not hit the end faces of the workpiece (1) and the base metal (11) side of the grinding wheel (13) and is not bounced back. Specifically, the inclination angle α of the extension line C with respect to the grinding wheel shaft (12) (the center axis J of the grinding wheel shaft (12)) is set to 20 degrees or less. Also, 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 made larger 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 grindstone (13) side is either flush with the end face of the base metal (11) on the grindstone (13) side or is located farther from the grindstone (13) than the end face of the base metal (11) on the grindstone (13) side. Conversely, if the injection unit (21) is located closer to the grindstone (13) than the end face of the base metal (11) on the grindstone (13) side, it is necessary to lengthen the grindstone shaft (12) (specifically, the portion between the base metal (11) and the grindstone (13)) to prevent contact between the injection unit (21) and the workpiece (1). This reduces the rigidity of the grindstone shaft (12).

[0032] <Shaft-mounted grindstone> As described above, in order to reduce the distance between the ejection hole (22) of the ejection unit (21) and the grindstone shaft (12) and to set the inclination angle α of the center line (extension line C) of the ejection hole (22) with respect 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 Fig. 7, the base metal (11) of the grindstone (10) may have a truncated cone portion (15) with a grindstone shaft (12) provided at its apex. The inclination angle θ of the outer circumferential surface of the truncated cone portion (15) at the apex of the grindstone shaft (12) (central axis J) is equal to or greater than 0° and equal to or less than approximately 20°. Furthermore, the step between the outer circumferential surface of the truncated cone portion (15) and the outer circumferential surface of the grindstone shaft (12) at the apex of the truncated cone portion (15) is equal to or less than approximately 5 mm.

[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), decreases. Therefore, in order to secure a space for installing the injection unit (21) so that the injection hole (22) (extension line C) faces the direction of the grinding part of the workpiece (1), a concave surface (15a) may be provided on the outer peripheral surface of the truncated cone portion (15) of the base metal (11) as shown in Fig. 7. This makes it easy 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 shaft grinding wheel (10). For example, the inclination angle θ of the concave surface 15a of the truncated cone portion 15 with respect to the grindstone shaft 12 (central axis J) may be 0° or more and 20° or less 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 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 truncated cone portion 15 with respect to the central axis J of the grindstone shaft 12.

[0035] The shape of the base metal (11) is a combination of a truncated cone portion (15) having an outer circumferential 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 a wheel head (20) is inserted, but in the example shown in Fig. 7, the outer circumferential surface of the truncated cone portion (15) is replaced with a curved concave surface (15a). As shown in Fig. 7, when the mounted grindstone (10) is viewed from a direction perpendicular to the grindstone shaft (12), a curve (for example, a parabola or a circular arc) that is a concave surface (15a) with an inclination angle θ of about 0 to 20° with respect to the grindstone shaft (12) starts to extend from the top of the truncated cone portion (15) that has a diameter slightly (for example, about 1 to 2 mm) larger than the diameter of the grindstone (13), and the inclination angle θ changes significantly toward the bottom of the truncated cone portion (15). The curved line is connected to the outer circumferential surface of a cylindrical portion (16) having a diameter larger than that of the grindstone (13) at an angle φ of 40° or more and 90° or less.

[0036] In the shape of the base metal (11) shown in FIG. 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 into a concave surface (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] The configuration of the shaft-mounted grindstone (10) shown in FIG. 7 is an example, and as long as the inclination angle θ of the outer circumferential surface of the truncated cone portion (15) with respect to the grindstone shaft (12) (central axis J) at the apex (end portion on the grindstone (13) side) of the truncated cone portion (15) is between 0° and about 20°, the ejection holes (22) can be drilled in a desired direction even if the entire outer circumferential surface of the truncated cone portion (15) is not made into a concave surface (15a). Specifically, only the outer circumferential surface near the apex of the truncated cone portion (15) may be made into a concave surface. Alternatively, the outer circumferential surface of the truncated cone portion (15) may be made into a multiple 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 about 20°.

[0038] <Injection hole location> In order to ensure that the grinding fluid discharged from the injection hole (22) of the injection unit (21) hits the outer peripheral surface of the grindstone (13), the injection unit (21) and the shaft-mounted grindstone (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) on the grindstone (13) side and the end face of the grindstone (13) on the base metal (11) side (the axial length of the grindstone shaft (12) where the grindstone (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 grindstone shaft (12) (center axis J) is 20 degrees or less, for example, 16 degrees. Compared to the radius D1 of the grindstone (13), the radius D2 of the top of the base metal (11) is larger by about 1 to 3 mm, 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 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 circumferential surface of the grinding wheel (13).

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

[0042] 9, the injection unit (21) is configured, for example, in a semicircular or U-shaped shape so as to surround a part (about half the circumference in this example) of the outer periphery of the base metal (11) (the truncated cone portion (15)) in order to facilitate removal of the injection unit (21). When the grinding fluid supply unit (30) is configured from a 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 the embodiment is a grinding method for grinding the inner diameter of a workpiece (1) by rotating a grindstone (13) attached to a grindstone spindle (12) protruding from a base metal (11). The distance between the base metal (11) and the workpiece (1) during grinding changes, and the distance is 5 mm or less when grinding the innermost part of the workpiece (1). Grinding fluid is discharged 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).

[0044] In the grinding method of the embodiment, even if the grindstone 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 circumferential surface of the base metal (11) can supply sufficient grinding fluid to the grinding point of the workpiece (1). This makes it possible to suppress grinding burn and to suppress wear of the grindstone (13), thereby extending the life of the shank grindstone. In addition, since the grindstone spindle (12) can be shortened, it is possible to suppress a decrease in processing accuracy caused by bending of the grindstone spindle (12), and 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 the embodiment performs internal grinding of the workpiece (1) by rotating a grindstone (13) attached to a grindstone spindle (12) protruding from a base metal (11). The grinding device (100) includes an injection unit (21) installed so as 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 discharged from the injection hole (22) is supplied to the grinding location of the workpiece (1).

[0046] In the grinding device (100) of the embodiment, even if the grindstone 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 circumferential surface of the base metal (11) can supply sufficient grinding fluid to the grinding point of the workpiece (1). This makes it possible to suppress grinding burn and to suppress wear of the grindstone (13) to extend the life of the shaft-mounted grindstone. In addition, since the grindstone spindle (12) can be shortened, it is possible to suppress a decrease in processing accuracy caused by bending of the grindstone spindle (12), and to 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 arranged to face the machining 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 arranged to face the machining 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 arranged to face the machining hole. In Comparative Examples 1 and 2 shown in FIG. 10 and FIG. 11, the same elements as those in the embodiment shown in FIG. 3 are given the same symbols. As described above, it is desirable to make the grinding wheel spindle as short as possible to ensure rigidity, but when the distance between the base metal or wheel head of the grinding wheel spindle and the workpiece is about 5 mm or less, the base metal or wheel head blocks the machining hole of the workpiece as in Comparative Example 2 shown in FIG. 11, and therefore the grinding fluid nozzle cannot be appropriately arranged. This can result in an insufficient supply of grinding fluid to the grinding point of the workpiece, causing problems such as grinding burn (where the temperature of the grinding point reaches 500°C or higher) and shortening the life of the grinding wheel.

[0048] In the grinding device (100) of the embodiment, a plurality of small-diameter jet holes (22) of 2 mm or less may be arranged near the outer circumferential surface of the base metal (11). This allows the grinding fluid discharged from the jet holes (22) to easily enter the gap between the inner wall surface of the processed hole of the workpiece (1) and the grindstone shaft (12), making it easier to supply the 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 jet hole (22) with respect to the grindstone shaft (12) (center axis J) is 20 degrees or less, and each jet hole (22) may be drilled so that the extension line C hits the outer circumferential surface of the grindstone (13). In this way, the grinding fluid can be efficiently supplied to the grinding point of the workpiece (1) from the gap between the inner wall surface of the processed hole of the workpiece (1) and the grindstone shaft (12).

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

[0050] (Other embodiments) Although the embodiment and modifications have been described above, it will be understood that various modifications of form and details are possible without departing from the spirit and scope of the claims. In addition, the above embodiment, modifications, and other embodiments may be combined or substituted as appropriate. [Industrial Applicability]

[0051] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for a grinding method and a grinding apparatus. [Explanation of symbols]

[0052] 1 Workpiece 11 base money 12 Grindstone spindle 13. Grindstone 15 Cone truncated part 21 Injection unit 22 Injection hole 100 Grinding equipment

Claims

1. A grinding method for grinding an inner diameter of a workpiece (1) by rotating a grindstone (13) attached to a grindstone spindle (12) protruding from a base metal (11), comprising the steps of: The distance between the base metal (11) and the workpiece (1) during grinding changes, and the distance is 5 mm or less when the innermost portion of the workpiece (1) is ground. A grinding fluid is discharged from a jet unit (21) installed so as to cover the outer peripheral surface of the base metal (11) and is supplied to the grinding portion of the workpiece (1). Grinding method.

2. A grinding device for grinding the inner diameter of a workpiece (1) by rotating a grindstone (13) attached to a grindstone spindle (12) protruding from a base metal (11), a spray unit (21) that is installed so as to cover an outer peripheral surface of the base metal (11) and sprays a grinding fluid; The injection unit (21) is provided with an injection hole (22) so that the grinding fluid discharged from the injection unit (21) is supplied to a grinding portion of the workpiece (1). Grinding equipment.

3. 3. The grinding apparatus according to claim 2, As the injection holes (22), 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). Grinding equipment.

4. 4. The grinding apparatus according to claim 3, an inclination angle α of the center lines of the plurality of holes (22) with respect to the grindstone spindle (12) is 20 degrees or less; The plurality of holes (22) are drilled so that an extension of the center line contacts the outer circumferential surface of the grinding wheel (13). Grinding equipment.

5. The grinding apparatus according to any one of claims 2 to 4, The base metal (11) has a truncated cone portion (15) on the top of which the grindstone shaft (12) is provided, an inclination angle θ of an outer circumferential surface of the truncated cone portion (15) with respect to the grindstone 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°; Grinding equipment.

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