Grinder

Abstract

To provide a grinder that can be stably and accurately rotated so as to grind an inner peripheral surface of a work-piece while securing processing accuracy sufficiently.SOLUTION: A grinder 10 comprises: a first rotating roll 12 arranged above a work-piece 1; a second rotating roll 11, arranged below the work-piece, which rotates the work-piece around a center axis O1 at a processing position S in cooperation with the first rotating roll; a shoe 13 that holds the work-piece at the processing position; and a pressure member 16 having a center part 15 that intrudes into the work-piece while contacting an opening edge of a first opening part 4. The first rotating roll and the second rotating roll rotate the work-piece while making a second opening part 5 open outward. The pressure member enables the center part to rotate together with the work-piece while pressing the center part against the work-piece. The center part has a guide surface 15a that guides the work-piece to rotate so that the work-piece rotates around the center axis, by contacting the whole circumference of the opening edge of the first opening part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a grinding machine. [Background technology]

[0002] BACKGROUND ART As an apparatus for grinding the inner peripheral surface of a cylindrical workpiece suitable for use in bearings and the like, for example, a grinding machine that grinds the workpiece while rotating it at a processing position is known (for example, Patent Document 1). The grinding machine mainly comprises an upper roll (retreat roll) and a lower roll (support roll) that rotate the workpiece that has been supplied to the processing position, a shoe that slidably contacts the workpiece and holds it in the processing position, and a grinding means having a grinding wheel that grinds the inner surface of the workpiece at the processing position.

[0003] In this grinding machine, the workpiece is sandwiched between the upper and lower rolls and rotated synchronously to rotate the workpiece at the processing position. A grinding wheel is placed inside the rotating workpiece and pressed against the inner peripheral surface of the part of the workpiece held by the shoe. In this way, the inner peripheral surface of the workpiece is ground while being sandwiched between the shoe and the grinding wheel in the thickness direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5026240 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional grinding machines described above, in order to grind the inner peripheral surface of a workpiece while ensuring sufficient machining accuracy, it is necessary to rotate the workpiece stably and accurately about its central axis, and therefore it is necessary to rotate the upper roll and lower roll in contact with the outer peripheral surface of the workpiece in an appropriate synchronized manner. In addition, it is preferable to arrange the upper and lower rolls near the processing area where stress acts on the workpiece due to the grinding stone being pressed against the inner peripheral surface of the workpiece. This is because the upper and lower rolls can support the outer peripheral surface of the roll near the processing area. Therefore, in this case, stress from the grinding stone can be easily absorbed, and rotational runout and the like can be suppressed, making it easy to rotate the workpiece stably.

[0006] However, for example, in the case of a long workpiece that is long in the direction of its central axis, the center of gravity of the workpiece itself is located away from the machining area in the direction of the central axis. This makes it difficult for the upper and lower rolls to support the area around the center of gravity of the workpiece, making it prone to rotational runout. This makes the workpiece tilt, making rotation unstable and making it difficult to rotate it accurately in a stable position. As a result, it becomes difficult to machine the inner surface of the workpiece with sufficient machining accuracy, leaving room for improvement.

[0007] Furthermore, for example, in the case of a workpiece with a stepped shape (a stepped workpiece) with different outer diameters, the center of gravity is located closer to the large diameter portion than to the small diameter portion. Therefore, even if the workpiece is not long, when machining the inner surface of the small diameter portion, the center of gravity is located farther from the machining area. Therefore, even when machining a special workpiece such as a stepped workpiece, rotational runout is likely to occur, just as with long workpieces, making it difficult to machine the inner surface of the workpiece with sufficient machining accuracy. Therefore, there is still room for improvement.

[0008] The present invention has been made in consideration of these circumstances, and its purpose is to provide a grinding machine that can rotate a variety of workpieces, including long workpieces and stepped workpieces, stably and accurately, and can grind the inner surfaces of the workpieces while ensuring sufficient processing accuracy. [Means for solving the problem]

[0009] (1) A grinding machine according to the present invention is a grinding machine that grinds an inner peripheral surface of a cylindrical workpiece having a first opening and a second opening while rotating the workpiece around a central axis, and includes: a first rotating roll that is arranged above the workpiece at a processing position and is capable of contacting the outer peripheral surface of the workpiece; a second rotating roll that is arranged below the workpiece and is capable of contacting the outer peripheral surface of the workpiece, and that cooperates with the first rotating roll to rotate the workpiece around the central axis at the processing position; a shoe that is arranged along the central axis and slidably abuts against the outer peripheral surface of the workpiece to hold the workpiece at the processing position; and and a pressure member having a center portion that penetrates into the workpiece while contacting the opening edge of the opening, wherein the first rotating roll and the second rotating roll rotate the workpiece at the processing position with the second opening open to the outside, and the pressure member is capable of rotating together with the workpiece around the central axis while pressing the center portion against the workpiece along the central axis, and the center portion has a guide surface that contacts the opening edge of the first opening over its entire circumference to guide the rotation of the workpiece so that it rotates around the central axis.

[0010] According to the grinding machine of the present invention, the first rotating roll and the second rotating roll cooperate to rotate a workpiece placed at the processing position around the central axis. At this time, the shoe is slidably abutted against the outer peripheral surface of the rotating workpiece, allowing the workpiece to rotate while being held at the processing position. The second opening of the workpiece opens toward the outside at the processing position. Therefore, a grinding tool such as a grinding wheel can be set inside the workpiece through the second opening. This allows the grinding tool to be pressed against the inner peripheral surface of the workpiece so as to sandwich the workpiece between the grinding tool and the shoe in the thickness direction, thereby grinding the inner peripheral surface of the workpiece.

[0011] In particular, the center portion of the pressure member is pressed against the first opening of the workpiece, which is located opposite the second opening where the grinding tool is set, and is inserted into the workpiece. This allows the pressure member, including the center portion, to rotate in synchronization with the workpiece while fixing the workpiece in the axial direction (direction along the central axis). Therefore, the workpiece can be rotated while supporting the first opening side of the workpiece, which is located opposite the processing area (the second opening side of the workpiece) where grinding is performed by the grinding tool, using the center portion. Moreover, because the guide surface of the center portion contacts the opening edge of the first opening along the entire circumference, tilting of the workpiece during rotation is unlikely to occur. Therefore, the workpiece can be centered during rotation, making it easy to rotate the workpiece stably around the central axis.

[0012] Therefore, the occurrence of rotational runout and the like can be suppressed, and the workpiece can be rotated with high precision in a stable posture. As a result, the inner peripheral surface of the workpiece can be ground while ensuring sufficient processing accuracy. In particular, the workpiece is centered by inserting a center portion having a guide surface into the first opening of the workpiece, which is located on the opposite side of the processing area where grinding is performed by the grinding tool. Therefore, even a variety of workpieces, such as long workpieces whose center of gravity is likely to be far from the processing area or stepped workpieces with different outer diameters, can be rotated stably and with high precision.

[0013] (2) The guide surface may be formed in a tapered shape centered on the central axis and in contact with the opening edge of the first opening over the entire circumference.

[0014] In this case, because the guide surface of the center portion is formed in a tapered shape, when the center portion is inserted into the first opening of the workpiece, the guide surface can be in line contact or surface contact with the opening edge of the first opening along its entire circumference. In particular, because the guide surface is formed in a tapered shape centered on the central axis, even if the workpiece exhibits a tilting behavior during rotation, the orientation of the workpiece can be changed to follow the guide surface. Therefore, this behavior can be suppressed, and the workpiece can easily be returned to its original orientation. Therefore, the workpiece can be easily rotated stably around the central axis.

[0015] (3) A guide cylinder may be provided that surrounds the pressure member from the outside and accommodates the pressure member therein, and the pressure member may be supported by the guide cylinder so as to be rotatable about the central axis.

[0016] In this case, the entire pressure member, including the center portion, can be rotatably supported using the guide tube, so that the workpiece can be rotated around the central axis together with the pressure member more stably, thereby enabling the inner peripheral surface of the workpiece to be ground with even greater precision.

[0017] (4) A supply mechanism may be provided for supplying a fluid between the pressure member and the guide tube, and the pressure member may be supported by the supply of fluid so as to be rotatable in a non-contact state relative to the guide tube.

[0018] In this case, the pressure member can be supported so as to float in midair by using a fluid, such as air, supplied between the pressure member and the guide tube using a supply mechanism, and the pressure member can be supported in a non-contact state with respect to the guide tube. This allows the workpiece to rotate together with the pressure member with little resistance, enabling the inner peripheral surface of the workpiece to be ground efficiently.

[0019] (5) A switching mechanism may be provided that switches the position of the pressure member between a pressing position in which the center portion is pressed against the workpiece and a release position in which the center portion is separated from the workpiece and the pressure is released by moving the pressure member along the central axis relative to the guide tube.

[0020] In this case, the pressure member can be moved by the switching mechanism to quickly switch between the pressing position and the release position. Therefore, the workpiece can be easily set at the processing position. Furthermore, the pressing force of the center portion against the workpiece can be adjusted according to the size of the workpiece being used, making it possible to make a grinding machine that can handle a variety of workpieces.

[0021] (6) The second rotating rolls may be provided in pairs spaced apart along the central axis, and the first rotating roll and the shoe may be provided along the central axis and positioned between the pair of second rotating rolls.

[0022] In this case, since a pair of second rotating rolls are provided at a distance along the central axis, even a long workpiece can be rotated around the central axis while maintaining a stable posture. In particular, the pair of second rotating rolls can be used to support the workpiece located at the processing position from below, and the first rotating roll and shoe are disposed between the pair of second rotating rolls, so the inner peripheral surface of the workpiece can be ground while the processing region (second opening side) of the workpiece is stably supported and rotated.

[0023] (7) The workpiece may be formed in a stepped shape having a plurality of different outer diameters, and the pair of second rotating rolls may be arranged so as to contact the outer peripheral surface of the part of the workpiece having a common outer diameter.

[0024] In this case, the stepped workpiece can be arranged so that both of the pair of second rotating rolls come into contact with the portion having a common outer diameter, for example, the outer peripheral surface of the small diameter portion. If one second rotating roll contacts the outer peripheral surface of the small diameter portion of the workpiece and the other second rotating roll contacts the outer peripheral surface of the large diameter portion of the workpiece, the peripheral speeds of the two second rotating rolls will differ. This can easily hinder stable rotation of the workpiece. In this regard, by having the pair of second rotating rolls contact the outer peripheral surfaces of the parts of the workpiece that have a common outer diameter, the workpiece can be rotated more stably due to the synergistic effect with the center portion.

[0025] (8) The first rotating roll, the second rotating roll, and the shoe may be disposed closer to the second opening than the center of gravity of the workpiece.

[0026] In this case, even if the center of gravity of the workpiece is separated from the machining area (second opening side) of the workpiece, such as in the case of a long workpiece or a stepped workpiece having a plurality of different outer diameters, the first opening side can be rotationally supported using the center portion while stably supporting the rotation of the machining area of ​​the workpiece. Therefore, even for a long workpiece or a stepped workpiece, the inner peripheral surface can be ground with high precision while suppressing rotational runout, etc. [Effects of the Invention]

[0027] The grinding machine according to the present invention can rotate a variety of workpieces, including long workpieces or stepped workpieces, stably and accurately, and can grind the inner surface of the workpiece while ensuring sufficient processing accuracy. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a longitudinal sectional view showing an embodiment of a grinding machine according to the present invention, illustrating a state in which a workpiece is rotationally supported at a processing position. [Figure 2] FIG. 2 is a perspective view showing the overall configuration of the grinding machine shown in FIG. [Figure 3] 3 is a perspective view of the grinding machine shown in FIG. 2, seen from a different direction. [Figure 4] FIG. 3 is a perspective view of the grinding machine shown in FIG. 2, seen from a different direction. [Figure 5]FIG. 3 is a perspective view of the grinding machine shown in FIG. 2, seen from a different direction. [Figure 6] FIG. 3 is an enlarged perspective view of the periphery of the workpiece shown in FIG. 2. [Figure 7] FIG. 7 is a perspective view showing a state in which the front plate is removed from the state shown in FIG. 6. [Figure 8] FIG. 8 is a perspective view showing a state in which a pair of lower rolls has been removed from the state shown in FIG. 7. [Figure 9] 8 is a side view of the workpiece, a pair of lower rolls, and an upper roll shown in FIG. 7, as viewed from the central axis direction of the workpiece. [Figure 10] 8 is a side view of the workpiece, a pair of lower rolls, and an upper roll shown in FIG. 7, as viewed from the radial direction of the workpiece. FIG. [Figure 11] FIG. 7 is a perspective view showing a state in which the work and part of the accommodation unit are mainly removed from the state shown in FIG. 6. [Figure 12] FIG. 7 is a vertical cross-sectional view of the workpiece, pressure member, etc. taken along line AA shown in FIG. 6. [Figure 13] FIG. 13 is an enlarged longitudinal sectional view of the workpiece and the periphery of the center portion shown in FIG. 12. [Figure 14] 13 is a vertical cross-sectional view showing a state in which the pressure member shown in FIG. 12 is located at a release position. FIG. [Figure 15] FIG. 10 is a vertical cross-sectional view showing a modified example of the grinding machine according to the present invention. [Figure 16] 2 is a longitudinal sectional view showing a state in which a long workpiece having a constant diameter over its entire length is held at a processing position in the grinding machine shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a grinding machine according to the present invention will be described below with reference to the drawings. As shown in Figures 1 and 2, the grinding machine 10 of this embodiment is a device that grinds the inner surface of the workpiece 1 by using a grinding wheel 17, which is a grinding tool, while rotating the workpiece 1 that has been supplied to the processing position S around the central axis O1 of the workpiece 1 at the processing position S. In FIG. 1, some components of the grinding machine 10 are not shown.

[0030] The workpiece 1 is formed in a cylindrical shape having a first opening 4 and a second opening 5. In this embodiment, the workpiece 1 is formed in a two-stage stepped shape having two different outer diameters. Specifically, the workpiece 1 is formed in a two-stage cylindrical stepped shape having a small diameter portion 2 and a large diameter portion 3 whose outer diameter is larger than that of the small diameter portion 2. The opening in the large diameter portion 3 of the workpiece 1 functions as a first opening 4, and the opening in the small diameter portion 2 functions as a second opening 5.

[0031] In the illustrated example, the workpiece 1 is formed so that the length along the central axis O1 of the large diameter portion 3 is slightly longer than that of the small diameter portion 2. Furthermore, the large diameter portion 3 is formed to be slightly thicker than the small diameter portion 2. Therefore, the center of gravity G of the workpiece 1 is located closer to the first opening 4 than the center position of the workpiece 1.

[0032] In this embodiment, the direction along the central axis O1 of the workpiece 1 is defined as the left-right direction L1. Furthermore, the direction perpendicular to the left-right direction L1 and the up-down direction is defined as the front-to-back direction L2. Within the left-to-right direction L1, the direction from the first opening 4 of the workpiece 1 toward the second opening 5 is defined as the left side LH, and the direction from the second opening 5 toward the first opening 4 is defined as the right side RH. Furthermore, one side of the front-to-back direction L2 is defined as the front FW, and the other side is defined as the rear BK.

[0033] As shown in Figures 1 to 5, the grinding machine 10 includes an upper roll (first rotating roll according to the present invention) 12 arranged above the workpiece 1 arranged at the processing position S, a lower roll (second rotating roll according to the present invention) 11 arranged below the workpiece 1 arranged at the processing position S, a main shoe (shoe according to the present invention) 13 and an auxiliary shoe 14 that hold the workpiece 1 at the processing position S, a pressure member 16 having a center portion 15 that penetrates into the workpiece 1 while contacting the opening edge of the first opening 4, and a grinding mechanism 18 equipped with a grinding wheel 17.

[0034] (Lower roll) 1, 2, and 6 to 8, the lower roll 11 is disposed below the workpiece 1 disposed at the processing position S, and is disposed so as to be able to contact the outer peripheral surface of the workpiece 1 from below. A pair of lower rolls 11 is provided, and is disposed at an interval in the left-right direction L1 along the central axis O1 of the workpiece 1. Therefore, the grinding machine 10 of this embodiment is configured to rotate the workpiece 1 at the processing position S using two lower rolls 11 and one upper roll 12.

[0035] The pair of lower rolls 11 are arranged below the small diameter portion 2 of the workpiece 1 and are capable of contacting the outer circumferential surface of the small diameter portion 2. Therefore, the pair of lower rolls 11 are arranged closer to the second opening 5 than the center of gravity G of the workpiece 1. In particular, the pair of lower rolls 11 are arranged so as to contact both the outer circumferential surface of the small diameter portion 2 rather than contacting each of the large diameter portion 3 and the small diameter portion 2 of the workpiece 1, which have different outer diameters. Therefore, the pair of lower rolls 11 are in contact with the outer circumferential surface of the portion of the workpiece 1 that has a common outer diameter (small diameter portion 2).

[0036] The pair of lower rolls 11 are formed to have the same diameter and are attached so as to be unable to rotate with respect to the lower roll shaft portion 20, which rotates about the first rotation axis M1. This allows the pair of lower rolls 11 to rotate about the first rotation axis M1 in synchronization with each other as the lower roll shaft portion 20 rotates.

[0037] As shown in Figures 2 to 5, the lower roll shaft portion 20 is disposed below the workpiece 1 and extends in the left-right direction L1. A middle portion of the lower roll shaft portion 20 is held by a lower roll holding portion 21 so as to be rotatable about a first rotation axis M1. The lower roll holding portion 21 is assembled integrally with the first fixed block 30. A lower roll pulley 22 is attached to the right end portion of the lower roll shaft portion 20 so as not to rotate.

[0038] The first fixed block 30 has a first bottom wall portion 31 which has a predetermined thickness in the vertical direction and is formed in a rectangular shape in a plan view extending in the front-to-back direction L2 and the left-to-right direction L1, and a support wall portion 32 which extends upward from the left side portion of the first bottom wall portion 31. The first bottom wall 31 is integrally combined from above with a base plate (not shown) via a plurality of fixing bolts or the like. This fixes the entire first fixed block 30 to the base plate so that it cannot be displaced. The support wall 32 includes a support wall main body 33 and a swing arm 34 that extends upward from the support wall main body 33.

[0039] The upper end of the swing arm 34 is formed in a semicircular shape that is convex upward in a side view seen from the front-rear direction L2, and a shaft hole (not shown) is formed in the upper end of the swing arm 34, penetrating the upper end in the left-right direction L1.

[0040] (Top roll) 1, 2, and 6 to 8, the upper roll 12 is disposed above the workpiece 1 disposed at the processing position S, and is disposed so as to be able to contact the outer peripheral surface of the workpiece 1 from above. The upper roll 12 is disposed above the small diameter portion 2 of the workpiece 1 so as to be located at the center of the pair of lower rolls 11 in the left-right direction L1, and is capable of contacting the outer peripheral surface of the small diameter portion 2. As a result, the upper roll 12 is positioned closer to the second opening 5 than the center of gravity G of the workpiece 1. The upper roll 12 also cooperates with the pair of lower rolls 11 to support the rotation of the workpiece 1 in a well-balanced manner at the processing position S.

[0041] The upper roll 12 is formed to have the same diameter as the pair of lower rolls 11, and is attached non-rotatably to an upper roll shaft portion 40 that rotates about a second rotation axis M2. 2 to 5, the upper roll shaft portion 40 is disposed above the workpiece 1 and extends in the left-right direction L1. As a result, the upper roll shaft portion 40 is disposed parallel to the lower roll shaft portion 20.

[0042] The upper roll shaft section 40 is disposed slightly forward FW than the lower roll shaft section 20. As a result, as shown in Fig. 9, an imaginary line N connecting the first rotation axis M1 of the lower roll shaft section 20 and the second rotation axis M2 of the upper roll shaft section 40 is inclined with respect to the up-down direction. However, this is not limited to this case, and for example, the lower roll shaft section 20 and the upper roll shaft section 40 may be disposed side by side in the up-down direction with the positions of the lower roll shaft section 20 and the upper roll shaft section 40 aligned in the front-rear direction L2 so that the imaginary line N is parallel to the up-down direction. In addition, in a side view seen from the direction of the central axis O1, a space formed between the pair of lower roll 11 and upper roll 12 is defined as a processing position S (see FIG. 9).

[0043] Similar to the lower roll shaft portion 20, the upper roll shaft portion 40 has a middle portion rotatably held about a second rotation axis M2 by an upper roll holding portion 41. An upper roll pulley 42 is non-rotatably attached to the right end portion of the upper roll shaft portion 40. An upper wall block 43 having a predetermined thickness in the up-down direction and extending toward the rear BK is integrally formed with the upper roll holding portion 41. The upper wall block 43 is formed in a rectangular shape in a plan view extending in the left-right direction L1 and the front-rear direction L2, and is disposed above the support wall portion 32. A bracket 45 incorporating a bearing 44 (see FIGS. 4 and 5) is integrally attached to the upper wall block 43.

[0044] The bracket 45 has an accommodation groove 46 that opens downward and in the front-rear direction L2, and is disposed above the swing arm 34 with the upper end of the swing arm 34 accommodated in the accommodation groove 46. The bracket 45 further has a pair of side wall portions 47 that are spaced apart in the left-right direction L1. The inner sides of the pair of side wall portions 47 form the accommodation groove 46. Therefore, the swing arm 34 is disposed inside the pair of side wall portions 47. A bearing 44 is mounted coaxially with a swing axis O2 extending in the left-right direction L1 on each of the pair of side walls 47. A swing shaft (not shown) inserted into a shaft hole formed in the upper end of the swing arm 34 is rotatably supported by the pair of bearings 44.

[0045] Therefore, the entire bracket 45 is supported by the swing arm 34 so as to be swingable up and down about the swing axis O2. This allows the upper roll 12 to swing up and down via the upper roll shaft portion 40, the upper roll holding portion 41, the upper wall block 43, and the bracket 45 so as to move towards and away from the pair of lower rolls 11. Therefore, the upper roll 12 is capable of reciprocating movement between a set position where a processing position S is formed between the pair of lower rolls 11, and a retracted position spaced above the lower rolls 11. This makes it possible to perform operations such as setting the workpiece 1 at the processing position S before processing, rotating the workpiece 1 at the processing position S to perform processing (grinding), and discharging the workpiece 1 from the processing position S after processing.

[0046] The work of setting and discharging the workpiece 1 at the processing position S may be performed manually by an operator, or may be performed automatically by appropriately combining a workpiece 1 supply mechanism, discharge mechanism, etc. (not shown).

[0047] 3, the upper end of a coil spring (biasing member) 50 is integrally connected to the upper wall block 43 via a connecting portion. The coil spring 50 is arranged in the vertical direction and biases the upper wall block 43 downward using its elastic restoring force. The lower end of the coil spring 50 is connected to a support rod connected to a base plate (not shown). As a result, the upper roll 12 is constantly rotated downward around the swing axis O2 by the biasing force of the coil spring 50.

[0048] 4 and 5, a rear arm 48 extending toward the rear BK is formed on the bracket 45. A rectangular parallelepiped swing block 51 is attached to the rear arm 48. A cam rod 52 extending upward is attached to the rear portion of the swing block 51 by, for example, a screw connection. The cam rod 52 is in slidable contact with the outer peripheral surface of an eccentric cam 90 (described later) from below. Therefore, the cam rod 52 is capable of moving up and down as the eccentric cam 90 rotates.

[0049] Specifically, when the upper roll 12 is closest to the pair of lower rolls 11 and forms a processing position S between the pair of lower rolls 11, the cam rod 52 is in the uppermost position while contacting the eccentric cam 90. This makes it possible to restrict the upward movement of the swing block 51 about the swing axis O2, and to position the upper roll 12 at the set position. Therefore, the workpiece 1 can be sandwiched between the pair of lower rolls 11 and upper rolls 12, and the state in which the workpiece 1 is set at the processing position S can be maintained.

[0050] When the eccentric cam 90 rotates, the cam rod 52 moves downward so as to press the swing block 51 downward. This allows the upper roll 12 to move upward while pressing down the swing block 51 about the swing axis O2 against the bias of the coil spring 50. Therefore, the upper roll 12 can be positioned at a retracted position where it is separated from the pair of lower rolls 11. This allows operations such as setting the workpiece 1 at the processing position S and discharging the workpiece 1 to be performed.

[0051] (Roll rotation mechanism) The upper roll 12 configured as described above cooperates with the pair of lower rolls 11 to rotate the workpiece 1 around the central axis O1 at the processing position S. The grinding machine 10 is equipped with a roll rotation mechanism 60 that rotates the pair of lower rolls 11 and upper roll 12 in synchronization. As shown in Figures 2 to 4, the roll rotation mechanism 60 includes a roll belt 61 wound around the lower roll pulley 22 and the upper roll pulley 42, a drive pulley 62 that transmits rotational force to the pair of lower rolls 11 and upper rolls 12 via the roll belt 61, and a roll motor idler 63 that suppresses slack in the roll belt 61.

[0052] The roll belt 61 is an endless belt, and is wound around the lower roll pulley 22 and the upper roll pulley 42, as well as the drive pulley 62 and the roll motor idler 63. The drive pulley 62 is located midway between the lower roll pulley 22 and the upper roll pulley 42 in the vertical direction, and is disposed rearward (BK) from the lower roll pulley 22 and the upper roll pulley 42. The roll motor idler 63 is disposed forward (FW) from the drive pulley 62.

[0053] The drive pulley 62 is non-rotatably attached to an output shaft (not shown) of a drive motor 64 that is fixed to a second fixed block 70 that is disposed rearward on the BK side of the first fixed block 30 . The second fixed block 70 has a second bottom wall portion 71 which has a predetermined thickness in the vertical direction and is formed in a rectangular shape in a plan view extending in the front-to-back direction L2 and the left-to-right direction L1, and a fixed plate 72 which is formed integrally with the second bottom wall portion 71.

[0054] The second bottom wall portion 71 is integrally assembled from above to a base plate (not shown) via a plurality of fixing bolts or the like. This prevents the entire second fixed block 70 from being displaced relative to the base plate. The fixed plate 72 has a constant thickness in the left-right direction L1 and is formed in a plate shape that extends in the front-rear direction L2 and the up-down direction. The fixed plate 72 is disposed on the right side RH of the swing arm 34 and swing block 51 with a gap between them, and is formed to extend upward beyond the swing arm 34 and swing block 51.

[0055] The fixed plate 72 has a through-hole 73 (see FIGS. 4 and 5) that penetrates the fixed plate 72 in the left-right direction L1. The drive motor 64 is disposed on the right side RH of the fixed plate 72 and fixed to the fixed plate 72. The drive motor 64 is, for example, a servo motor or a stepping motor, and has an output shaft that protrudes through the through-hole 73 toward the left side LH of the fixed plate 72. The drive pulley 62 is non-rotatably attached to the output shaft of the drive motor 64. This allows the drive pulley 62 to rotate at a predetermined timing and rotation speed when the drive motor 64 is operated.

[0056] The roll motor idler 63 is attached by utilizing a third fixed block 80 that is disposed on the right side RH of the first fixed block 30 and on the front side FW of the second fixed block 70. The third fixed block 80 has a third bottom wall portion 81 which has a predetermined thickness in the vertical direction and is formed in a rectangular shape in a plan view extending in the front-to-back direction L2 and the left-to-right direction L1, and a flange piece 82 which extends upward from the third bottom wall portion 81.

[0057] The third bottom wall portion 81 is integrally combined from above with a base plate (not shown) via a plurality of fixing bolts or the like. This fixes the entire third fixing block 80 to the base plate so that it cannot be displaced. The flange piece 82 has a constant thickness in the left-right direction L1 and is formed in a plate shape that extends in the front-rear direction L2 and the up-down direction. A movable plate 83 extending in the vertical direction is fixed to the flange piece 82 so as to be displaceable relative to the flange piece 82. The roll motor idler 63 is supported by the movable plate 83 so as to be rotatable.

[0058] Therefore, by fixing the movable plate 83 to the flange piece 82 while adjusting the position of the movable plate 83 in the up-down direction and the front-rear direction L2, the position of the roll motor idler 63 can be adjusted, and a constant tension can be applied to the roll belt 61. In this way, the roll motor idler 63 can be used to prevent the roll belt 61 from becoming loose.

[0059] Since the roll rotation mechanism 60 configured as described above is provided, the roll belt 61 can be driven without slack by operating the drive motor 64. This allows the lower roll pulley 22 and the upper roll pulley 42 to rotate synchronously. Therefore, the pair of lower roll 11 and upper roll 12 can be rotated synchronously, and the workpiece 1 can be rotated around the central axis O1 at the processing position S.

[0060] 1 and 2, the pair of lower roll 11 and upper roll 12 rotates the workpiece 1 with the small diameter portion 2 of the workpiece 1 positioned on the left side LH at the processing position S. Therefore, the pair of lower roll 11 and upper roll 12 rotates the workpiece 1 at the processing position S with the second opening 5 facing outward.

[0061] As shown in FIGS. 4 and 5, a swing motor 91 for rotating the eccentric cam 90 is attached to the fixed plate 72 of the second fixed block 70 described above. The swing motor 91 is fixed to the fixed plate 72 while being disposed on the right side RH of the fixed plate 72. The swing motor 91 is fixed so as to be located rearward (BK) and above the drive motor 64. The swing motor 91 is, for example, a servo motor or a stepping motor, and has an output shaft (not shown) that protrudes to the left side LH of the fixed plate 72 through a through-hole (not shown).

[0062] An eccentric cam 90 is non-rotatably attached to the output shaft of the swing motor 91. This allows the eccentric cam 90 to rotate at a predetermined timing and rotation angle by operation of the swing motor 91. As described above, the cam rod 52 is in slidable contact with the outer peripheral surface of the eccentric cam 90 from below. Therefore, by operating the swing motor 91, the upper roll 12 can be swung about the swing axis O2, and moved between the set position and the retracted position.

[0063] (Main shoe, auxiliary shoe) As shown in FIGS. 1 and 2, the main shoe 13 and the auxiliary shoe 14 slidably contact the outer peripheral surface of the rotating workpiece 1, thereby holding the workpiece 1 at the processing position S. As shown in FIGS. 4 and 6 to 8, the main shoe 13 and the auxiliary shoe 14 are attached to the first fixed block 30 via a relay block 100. As shown in FIGS. The relay block 100 is fixed to the left side surface of the support wall main body 33 of the first fixed block 30. The relay block 100 has a constant thickness in the left-right direction L1 and is formed in the shape of a square block when viewed from the side in the left-right direction L1.

[0064] On the left side surface of the relay block 100, the auxiliary shoe 14, intermediate block 101, main shoe 13, and front plate 102 are arranged in this order so as to overlap in the left-right direction L1. The auxiliary shoe 14, intermediate block 101, main shoe 13, and front plate 102 are fixed integrally to the relay block 100 by a plurality of common fixing bolts or the like.

[0065] 9, 10, and 11, the main shoe 13 is disposed between the pair of lower rolls 11 along the central axis O1, and has a main tip portion 13a that slidably contacts the workpiece 1 from the rear BK side. The main tip portion 13a contacts the outer peripheral surface of the small diameter portion 2 of the workpiece 1, thereby pressing the workpiece 1 at the processing position S toward the pair of lower rolls 11 and upper roll 12 (see FIG. 9). In this way, the main shoe 13 cooperates with the lower roll 11 and upper roll 12 to hold the workpiece 1 at the processing position S.

[0066] 8, 10, and 11, the auxiliary shoe 14 is disposed to the right RH of the pair of lower rolls 11, and has an auxiliary tip 14a that slidably contacts the workpiece 1 from the rear BK side. The auxiliary tip 14a contacts the outer peripheral surface of the large diameter portion 3 of the workpiece 1, thereby pressing the workpiece 1 at the processing position S toward the pair of lower rolls 11 and upper roll 12. In this way, the auxiliary shoe 14 cooperates with the lower roll 11 and upper roll 12 to auxiliary hold the workpiece 1 at the processing position S. The auxiliary shoe 14 is not essential and may be omitted, but it is preferable to provide the auxiliary shoe 14 when the workpiece 1 is an elongated workpiece formed long along the central axis O1.

[0067] 8, 10, and 11, a workpiece support piece 103 that supplementarily supports the workpiece 1 from above is attached to the intermediate block 101. The workpiece support piece 103 is, for example, a thin, strip-shaped metal plate, with a base end attached to the upper surface of the intermediate block 101 and a tip end, which is a free end, that is in slidable contact with the large diameter portion 3 of the workpiece 1 from above. In the example shown, a pair of workpiece support pieces 103 are provided with an interval in the left-right direction L1.

[0068] 1, 2, and 6, the front plate 102 is disposed on the left side LH of the main shoe 13, and is disposed on the left side LH of the workpiece 1 positioned at the processing position S. The front plate 102 has a constant thickness in the left-right direction L1, and is formed in a rectangular shape that is longer in the front-rear direction L2 than in the up-down direction in a side view seen from the left-right direction L1. The front plate 102 is disposed so as to cover the workpiece 1 from the left side LH. As a result, the front plate 102 restricts the workpiece 1 positioned at the processing position S from moving to the left side LH, and the workpiece 1 can be positioned at the processing position S.

[0069] The front plate 102 is formed with a machined hole 102a penetrating the front plate 102 in the left-right direction L1. The machined hole 102a is arranged coaxially with the central axis O1 of the workpiece 1 and has a diameter equal to the inner diameter of the small diameter portion 2 of the workpiece 1. As a result, the second opening 5 of the small diameter portion 2 of the workpiece 1 opens to the outside through the machined hole 102a.

[0070] (Pressure member) As shown in Figures 11 and 12, a pressure member 16 having a center portion 15 that penetrates into the workpiece 1 while contacting the opening edge of the first opening 4 in the large diameter portion 3 of the workpiece 1 is arranged on the right side RH of the workpiece 1 located at the processing position S. The pressure member 16 comprises a cylindrical pressure tube 110 extending along the left-right direction L1, and an annular center portion (centering portion) 15 integrally combined with the pressure tube 110, and is arranged coaxially with the central axis O1 of the workpiece 1.

[0071] The pressure tube 110 includes a pressure tube main body 111 and an annular flange portion 112 that protrudes radially outward from the right end portion of the pressure tube main body 111. As shown in Fig. 13, the center portion 15 is integrally combined with the pressure tube main body 111 by, for example, fitting into an annular protrusion 113 formed on the left end face of the pressure tube main body 111. In this embodiment, the pressure tube 110 and the center portion 15 are formed separately and then combined together as an example, but this is not limited to this case, and the pressure tube 110 and the center portion 15 may also be formed integrally.

[0072] 13, a guide surface 15a having a cross-sectionally tapered shape centered on the central axis O1 is formed on the outer peripheral surface of the center portion 15. The guide surface 15a is formed so as to have a cross-sectionally tapered shape extending radially inward of the workpiece 1 as it approaches the left side LH (the workpiece 1 side), and is formed so as to extend continuously around the entire circumference of the center portion 15.

[0073] In this embodiment, an inclined surface 6 having a cross-sectional tapered shape centered on the central axis O1 is formed at the opening edge of the first opening 4 of the large diameter portion 3 of the workpiece 1. The inclined surface 6 is formed so as to have a cross-sectional tapered shape extending radially outward of the workpiece 1 as it moves toward the right side RH, and is also formed so as to extend continuously around the entire circumference of the workpiece 1. The inclination angle of the guide surface 15a corresponds to the inclination angle of the inclined surface 6.

[0074] 12, the pressure member 16 configured as described above is rotatable together with the workpiece 1 about the central axis O1 with the center portion 15 pressed against the workpiece 1 from the right side RH along the central axis O1. The guide surface 15a of the center portion 15 contacts the opening edge of the first opening 4 over the entire circumference, thereby guiding the rotation of the workpiece 1 about the central axis O1. Specifically, the guide surface 15a of the center portion 15 is in surface contact with the inclined surface 6 of the workpiece 1 over the entire circumference, thereby guiding the rotation of the workpiece 1.

[0075] 11 and 12, the pressure cylinder main body 111 is provided with a guide cylinder 130 that surrounds the pressure cylinder main body 111 from the outside in the radial direction and accommodates the pressure member 16 therein. In the illustrated example, the guide cylinder 130 is formed in a double-cylinder shape having an inner cylinder 120. However, the inner cylinder 120 is not essential and may not be provided.

[0076] As a result, the pressure member 16 is rotatably supported around the central axis O1 by the guide tube 130. A small gap is formed around the entire circumference of the pressure member 16 between the pressure member 16 and the guide tube 130 (specifically, between the pressure member 16 and the inner tube 120 that constitutes the guide tube 130).

[0077] A communication hole 131 penetrating the guide tube 130 is formed in a portion of the guide tube 130 located in the center in the left-right direction L1. Furthermore, a pair of O-rings 132 are provided at a distance in the left-right direction L1 on the outer peripheral surface of a portion of the guide tube 130 located on the left side LH of the communication hole 131. Similarly, a pair of O-rings 132 are provided at a distance in the left-right direction L1 on the outer peripheral surface of a portion of the guide tube 130 located on the right side RH of the communication hole 131. As a result, a total of four O-rings 132 are provided on the outer peripheral surface of the guide tube 130, with the communication hole 131 sandwiched between them.

[0078] (Containment Unit) As shown in FIG. 12, the grinding machine 10 includes a housing unit 140 that surrounds the entire guide tube 130 and the pressure tube 110 from the outside in the radial direction.

[0079] 2, 3, and 12, the storage unit 140 includes a first storage member 141, a second storage member 142, a third storage member 143, and a fourth storage member 144, which are arranged in this order along the left-right direction L1 from the workpiece 1 located at the processing position S to the right side RH. The storage unit 140 is configured by combining the first storage member 141, the second storage member 142, the third storage member 143, and the fourth storage member 144 with one another without any gaps by a plurality of fixing bolts or the like.

[0080] 8, the second accommodating member 142 is formed in a block shape having a constant thickness in the left-right direction L1, and is formed integrally with a relay block 100 that is fixed to the support wall main body 33 of the first fixed block 30. As a result, the second accommodating member 142 is supported by the first fixed block 30 via the relay block 100. 12, a second accommodating hole 150 is formed in the second accommodating member 142, penetrating the second accommodating member 142 in the left-right direction L1. The second accommodating hole 150 is formed coaxially with the central axis O1 of the workpiece 1 and has the same diameter as the outer diameter of the guide tube 130. As shown in FIG. 8, a first connection port 151 communicating with the communication hole 131 formed in the guide tube 130 is formed in the front wall surface of the second housing member 142 facing the forward FW side.

[0081] 2, 3, 8, and 12, the first housing member 141 is formed in a block shape having a certain thickness in the left-right direction L1, and is disposed so as to be located on the left side LH of the second housing member 142. The first housing member 141 is overlapped with the second housing member 142 with no gap between them, and is screwed to the second housing member 142 from the left side LH via a fixing bolt. As a result, the first housing member 141 and the second housing member 142 are combined together as a single unit.

[0082] As shown in Figure 12, the first accommodating member 141 is formed with a central hole 152 that penetrates the first accommodating member 141 in the left-right direction L1, and a first accommodating hole 153 that communicates with the central hole 152 and opens toward the right side RH. The central hole 152 is formed coaxially with the central axis O1 of the workpiece 1 and has the same diameter as the outer diameter of the center portion 15. The first accommodating hole 153 is formed coaxially with the central axis O1 of the workpiece 1 and has the same diameter as the outer diameter of the guide tube 130. Therefore, the first accommodating hole 153 and the second accommodating hole 150 are formed to have the same diameter and are arranged adjacent to each other in the left-right direction L1.

[0083] A portion of the first accommodating member 141 that is located on the left side LH of the first accommodating hole 153 functions as an annular first restricting flange 154. A central hole of the first restricting flange 154 functions as the central hole 152. A surface of the first restricting flange 154 facing the right side RH functions as a first restricting surface 154a that positions the guide tube 130 by contacting the guide tube 130 from the right side RH and restricting further movement of the guide tube 130 toward the left side LH.

[0084] 2, 3, 8, and 12, the third housing member 143 is formed in a block shape having a constant thickness in the left-right direction L1, and is disposed so as to be located on the right side RH of the second housing member 142. The third housing member 143 is overlapped with the second housing member 142 with no gap between them, and is screwed to the second housing member 142 from the right side RH via a fixing bolt. As a result, the third housing member 143 and the second housing member 142 are combined together as a single unit.

[0085] 12, a third accommodating hole 155 is formed in the third accommodating member 143, penetrating the third accommodating member 143 in the left-right direction L1. The third accommodating hole 155 is formed coaxially with the central axis O1 of the workpiece 1 and has the same diameter as the outer diameter of the guide tube 130. Therefore, the third accommodating hole 155 and the second accommodating hole 150 are formed to have the same diameter and are arranged adjacent to each other in the left-right direction L1.

[0086] 2, 3, 8, and 12, the fourth housing member 144 is formed in a block shape having a constant thickness in the left-right direction L1, and is disposed so as to be located on the right side RH of the third housing member 143. The fourth housing member 144 is overlapped with the third housing member 143 with no gap between them, and is screwed to the third housing member 143 from the right side RH via a fixing bolt. As a result, the fourth housing member 144 and the third housing member 143 are combined together as a single unit.

[0087] 12, a slide hole 160 is formed in the fourth accommodating member 144, penetrating the fourth accommodating member 144 in the left-right direction L1. A ring-shaped second restricting flange 161 is formed in a portion of the slide hole 160 located on the left side LH, protruding radially inward of the pressure cylinder main body 111. A center hole 162 of the second restricting flange 161 is formed coaxially with the central axis O1 of the workpiece 1 and has the same diameter as the outer diameter of the pressure cylinder main body 111.

[0088] The pressure tube body 111 is disposed in a central hole 162 of the second regulating flange 161 with the flange portion 112 disposed to the right RH of the second regulating flange 161. The surface of the second regulating flange 161 facing the right side RH functions as a second regulating surface 161a that comes into contact with the flange portion 112 from the right side RH and regulates further movement of the pressure tube 110 toward the left side LH (the workpiece 1 side).

[0089] Furthermore, an annular recess 163 recessed toward the right side RH is formed on the left end surface of the fourth accommodating member 144, which is in surface contact with the third accommodating member 143. Furthermore, the fourth accommodating member 144 is formed with a forward flow path 164 and a reverse flow path 165 for moving the pressure member 16 in the left-right direction L1. The forward flow path 164 opens into the slide hole 160 and also opens into the front wall surface facing the forward FW side of the fourth accommodating member 144. The reverse flow path 165 opens into the second restriction surface 161a and also opens into the front wall surface facing the forward FW side of the fourth accommodating member 144. Furthermore, a discharge flow path 166 that connects the inside of the recess 163 with the outside is formed in the fourth accommodating member 144.

[0090] As shown in Figures 2 and 3, a second connection port 167 communicating with the forward flow path 164 is formed on the front wall surface of the fourth accommodating member 144, and a third connection port 168 communicating with the reverse flow path 165 is also formed.

[0091] 3 and 12, a fourth connection port 170 is fixed to the fourth accommodating member 144 from the right side RH using a fixing bolt or the like. The fourth connection port 170 has an insertion portion 171 that protrudes from the left end surface toward the left side LH. The fourth connection port 170 is fixed to the fourth accommodating member 144 with the insertion portion 171 inserted inside the pressure cylinder main body 111. The insertion portion 171 is inserted into the pressure tube main body 111 while allowing the pressure member 16 to move in the left-right direction L1. A certain level of sealing is ensured between the insertion portion 171 and the pressure tube main body 111.

[0092] 12, the guide tube 130 is disposed inside the first accommodating hole 153, the second accommodating hole 150, and the third accommodating hole 155, with the guide tube 130 contacting the first restricting surface 154a of the first restricting flange 154 from the right side RH. The guide tube 130 is accommodated in the first accommodating hole 153, the second accommodating hole 150, and the third accommodating hole 155 via the O-ring 132, ensuring a certain level of sealing.

[0093] (supply mechanism) The pressure member 16 housed in the guide cylinder 130 is supported by the guide cylinder 130 so as to be rotatable about the central axis O1. Specifically, the grinding machine 10 of this embodiment is provided with a supply mechanism 180 that supplies, for example, air (fluid) between the pressure member 16 and the inner cylinder 120 that constitutes the guide cylinder 130. As shown in Fig. 3, a first air supply source 181 is connected to the first connection port 151 through a pipe (not shown). The operation of the first supply source 181 is controlled by a control unit (not shown), and it is possible to supply air, for example, at a predetermined timing, at a predetermined pressure, and for a predetermined supply time.

[0094] This allows air at a predetermined pressure to be supplied through the first connection port 151 and the communication hole 131 to a minute gap formed around the entire circumference between the inner tube 120 constituting the guide tube 130 and the pressure member 16. Therefore, the entire pressure member 16 can be supported so as to float in midair using air pressure, and the pressure member 16 can be rotatably supported in a non-contact state with respect to the guide tube 130.

[0095] Therefore, the guide tube 130 including the inner tube 120 can function as a hydrostatic bearing. The above-mentioned first supply source 181, first connection port 151, and communication hole 131 constitute a supply mechanism 180. Note that the first supply source 181 is not shown in the drawings other than Fig. 3. Furthermore, air supplied between the inner tube 120 and the pressure member 16 that constitute the guide tube 130 flows from the recess 163 shown in Fig. 12 to the discharge flow path 166, and is discharged from the inside of the discharge flow path 166 to the outside.

[0096] (switching mechanism) Furthermore, the pressure member 16 is disposed so as to be movable in the left-right direction L1 inside the guide tube 130. Specifically, the grinding machine 10 of this embodiment is equipped with a switching mechanism 190 that switches the position of the pressure member 16 between a pressing position P1 (see FIG. 12) where the center portion 15 is pressed against the workpiece 1, and a release position P2 where the center portion 15 is separated from the workpiece 1 and the pressing is released, as shown in FIG. 14, by moving the pressure member 16 along the central axis O1 of the workpiece 1 relative to the guide tube 130.

[0097] As shown in Fig. 3, a second air supply source 191 is connected to the second connection port 167 through piping (not shown). The operation of the second supply source 191 is controlled by a control unit (not shown), and it is possible to supply air at a predetermined timing, a predetermined pressure, and a predetermined supply time, for example. As a result, as shown in Fig. 12, air can be supplied into the slide hole 160 of the fourth accommodating member 144 through the second connection port 167 and the forward flow path 164. Note that the second supply source 191 is not shown in the drawings other than Fig. 3.

[0098] Therefore, the flange portion 112 can be pressed toward the left side LH (the workpiece 1 side) using air pressure, and the entire pressure member 16 can be moved to the left side LH. This allows the center portion 15 to enter the inside of the workpiece 1 while pressing it against the opening edge of the first opening 4, and the pressure member 16 can be positioned at the pressing position P1. This allows the guide surface 15a of the center portion 15 to come into contact with the inclined surface 6 of the first opening 4 of the workpiece 1 over the entire circumference.

[0099] Furthermore, as shown in Fig. 3, a third air supply source 192 is connected to the third connection port 168 through piping (not shown). The operation of the third supply source 192 is controlled by a control unit (not shown), and it is possible to supply air at a predetermined timing, a predetermined pressure, and a predetermined supply time, for example. As a result, as shown in Fig. 12, air can be supplied toward the flange 112 through the third connection port 168 and the reverse flow path 165. Note that the third supply source 192 is not shown in the drawings other than Fig. 3.

[0100] Therefore, by supplying air from the third supply source 192 while stopping the supply of air from the second supply source 191, it is possible to use air pressure to press the flange portion 112 toward the right side RH. Therefore, as shown in Fig. 14, the entire pressure member 16 can be moved to the right side RH, and the center portion 15 can be pulled out and separated from the first opening 4 of the workpiece 1. As a result, the entire pressure member 16 can be positioned at the release position P2.

[0101] When the pressure member 16 is positioned at the release position P2, the flange portion 112 comes into contact with the left end surface of the fourth connection port 170 from the left side LH. This allows the pressure member 16 to be maintained in a state where it is positioned at the release position P2. Furthermore, by positioning the pressure member 16 at the release position P2, the center portion 15 can be separated from the workpiece 1, making it possible to perform operations such as setting the workpiece 1 at the processing position S and removing the workpiece 1 from the processing position S.

[0102] The forward flow path 164, the second connection port 167, the second supply source 191, the reverse flow path 165, the third connection port 168, and the third supply source 192 described above constitute the switching mechanism 190. In particular, since the pressure member 16 can be moved using air pressure, it is possible to make the pressure tube 110 function as an air piston, and the entire accommodation unit 140 function as an air cylinder.

[0103] (Grinding mechanism) 1, the grinding mechanism 18 includes a grinding wheel 17 that grinds the inner peripheral surface of the workpiece 1, and a grinding wheel drive unit 18a that rotates the grinding wheel 17 around the central axis O1 of the workpiece 1 and moves the grinding wheel 17 in three-dimensional directions relative to the workpiece 1. Note that the grinding mechanism 18 including the grinding wheel 17 is not shown in the drawings other than FIG. After the workpiece 1 is set at the processing position S, the grindstone driving unit 18a inserts the grindstone 17 into the workpiece 1 through the second opening 5 and sets it therein. Furthermore, the grindstone driving unit 18a rotates the grindstone 17 and presses the grindstone 17 against the inner peripheral surface of the workpiece 1 rotating at the processing position S, thereby grinding the inner peripheral surface of the workpiece 1 so as to sandwich the workpiece 1 between the grindstone driving unit 18a and the main shoe 13.

[0104] 12, the interior of the workpiece 1 is in communication with the fourth connection port 170 (see FIG. 3) through the interior of the pressure member 16. Therefore, during processing (grinding) of the workpiece 1, it is possible to supply air to the interior of the workpiece 1 or to suck air from the interior of the workpiece 1 through the fourth connection port 170. This makes it possible to remove chips and the like generated by grinding with the grinding wheel 17 from the workpiece 1 during processing of the workpiece 1.

[0105] (Grinding machine action) Next, a case where the inner peripheral surface of the workpiece 1 is ground using the grinding machine 10 configured as described above will be described. When machining the workpiece 1, the workpiece 1 is set at the machining position S as shown in Figures 1 and 2. When setting the workpiece 1, the pressure member 16 is positioned at the release position P2 using air pressure as shown in Figure 14. Furthermore, by operating the swing motor 91 shown in Figure 4 to rotate the eccentric cam 90, the upper roll 12 is moved upward about the swing axis O2 and positioned at the retracted position. This makes it possible to secure space between the pair of lower roll 11 and upper roll 12 for setting the workpiece 1.

[0106] Then, the workpiece 1 is placed between the front plate 102 and the storage unit 140 by a supply device (not shown) or manually. Next, the swing motor 91 shown in FIG. 4 is operated to rotate the eccentric cam 90, which moves the upper roll 12 downward in cooperation with the biasing force of the coil spring 50 and positions it at the set position. This allows the workpiece 1 to be sandwiched between the pair of lower roll 11 and upper roll 12, and the workpiece 1 can be set at the processing position S.

[0107] 12, the pressure member 16 is positioned at the pressing position P1 using air pressure. This allows the center portion 15 to be inserted into the workpiece 1 while being pressed against the opening edge of the first opening 4. In particular, the guide surface 15a of the center portion 15 can be brought into surface contact with the inclined surface 6 of the workpiece 1 over the entire circumference, making it possible to guide the rotation of the workpiece 1.

[0108] Next, after the workpiece 1 is set as described above, the entire pressure member 16 shown in FIG. 12 is supported so as to float in midair inside the guide tube 130 using air pressure. Then, the drive motor 64 shown in FIG. 5 is operated to drive the roll belt 61, causing the pair of lower rolls 11 and upper rolls 12 to rotate synchronously. As a result, the pair of lower rolls 11 and upper rolls 12 cooperate to rotate the workpiece 1 placed at the processing position S around the central axis O1. At this time, as shown in FIGS. 8 and 9, the main shoe 13 and auxiliary shoe 14 are slidably abutted against the outer peripheral surface of the rotating workpiece 1, so that the workpiece 1 can be rotated while being held at the processing position S.

[0109] 1, the grinding wheel 17 is set inside the workpiece 1 through the second opening 5 of the workpiece 1 via the machining hole 102a in the front plate 102. Then, the rotating grinding wheel 17 is pressed against the inner peripheral surface of the rotating workpiece 1 so as to sandwich the workpiece 1 between the grinding wheel 17 and the main shoe 13, thereby grinding the inner peripheral surface of the workpiece 1.

[0110] In particular, the center portion 15 of the pressure member 16 is pressed against and enters the first opening 4 of the workpiece 1, which is located on the opposite side of the second opening 5 where the grinding wheel 17 is set. This allows the pressure member 16, including the center portion 15, to rotate in synchronization with the workpiece 1 while fixing the workpiece 1 in the axial direction (the direction along the central axis O1). Therefore, the workpiece 1 can be rotated while supporting the first opening 4 side of the workpiece 1, which is located on the opposite side of the processing area where grinding is performed by the grinding wheel 17 (the second opening 5 side of the workpiece 1), using the center portion 15. Moreover, since the guide surface 15a of the center portion 15 is in contact with the opening edge of the first opening 4 over the entire circumference, the workpiece 1 is less likely to tilt during rotation. Therefore, the workpiece 1 can be centered during rotation, and the workpiece 1 can be easily rotated stably around the central axis O1.

[0111] Therefore, it is possible to suppress the occurrence of rotational runout and the like, and to rotate the workpiece 1 with high precision in a stable posture. As a result, it is possible to grind the inner peripheral surface of the workpiece 1 while ensuring sufficient processing precision. In particular, the workpiece 1 can be centered by inserting the center portion 15 having the guide surface 15a into the first opening 4 of the workpiece 1 located on the opposite side of the processing area where grinding is performed by the grinding wheel 17, so that even a stepped workpiece 1 whose center of gravity position G is far from the processing area can be rotated stably and accurately.

[0112] As described above, the grinding machine 10 of this embodiment can rotate even a stepped workpiece 1 stably and accurately, and can grind the inner surface of the workpiece 1 while ensuring sufficient processing accuracy.

[0113] Furthermore, because the guide surface 15a of the center portion 15 is tapered, when the center portion 15 is inserted into the first opening 4 of the workpiece 1, as shown in Fig. 13, the guide surface 15a can be brought into surface contact with the inclined surface 6 of the first opening 4 along its entire circumference. In particular, because the guide surface 15a is tapered about the central axis O1, even if the workpiece 1 exhibits a tilting behavior during rotation, the attitude of the workpiece 1 can be changed to follow the guide surface 15a, thereby suppressing such behavior. Therefore, the workpiece 1 can be easily rotated stably around the central axis O1.

[0114] 1, a pair of lower rolls 11 are provided spaced apart in the left-right direction L1, so that even a long workpiece 1 can be rotated about the central axis O1 while maintaining a stable posture. In particular, the pair of lower rolls 11 can be used to support the workpiece 1 located at the processing position S from below, and the upper roll 12 and main shoe 13 are disposed between the pair of lower rolls 11, so that the inner peripheral surface of the workpiece 1 can be ground while the processing area (second opening 5 side) of the workpiece 1 is stably supported and rotated.

[0115] Moreover, since the pair of lower rolls 11, upper rolls 12, and main shoe 13 are positioned closer to the second opening 5 than the center of gravity G of the workpiece 1, even if the center of gravity G of the workpiece 1 is separated from the machining area (second opening 5 side) of the workpiece 1, the machining area of ​​the workpiece 1 can be stably rotationally supported while the center portion 15 can be used to rotationally support the first opening 4 side. Therefore, even if the workpiece 1 has a step, the inner peripheral surface can be ground with high precision while suppressing rotational runout and the like.

[0116] Furthermore, the pair of lower rolls 11 are arranged so as to come into contact with the outer circumferential surface of the small diameter portion 2, which is the portion having the common outer diameter. If a pair of lower rolls 11 contacts each of the portions of the workpiece 1 that have different outer diameters (small diameter portion 2, large diameter portion 3), the peripheral speed of one lower roll 11 will differ from the peripheral speed of the other lower roll 11. This can easily hinder stable rotation of the workpiece 1. In this regard, since the pair of lower rolls 11 are brought into contact with the outer peripheral surface of the small diameter portion 2 of the workpiece 1, which has a common outer diameter, the workpiece 1 can be rotated more stably due to the synergistic effect with the center portion 15.

[0117] Furthermore, since air can be supplied between the pressure member 16 and the guide tube 130 using the supply mechanism 180, the pressure member 16 can be supported so as to float in midair, and the pressure member 16 can be supported in a non-contact state with respect to the guide tube 130. Therefore, the workpiece 1 can be rotated together with the pressure member 16 with little resistance, and the inner peripheral surface of the workpiece 1 can be ground efficiently.

[0118] Furthermore, the pressure member 16 can be moved by the switching mechanism 190 to quickly switch between the pressing position P1 and the release position P2. This simplifies the process of setting the workpiece 1 at the processing position S. Furthermore, it is possible to adjust the pressing force of the center portion 15 against the workpiece 1 according to the size of the workpiece 1 being used, making it possible to provide a grinding machine 10 that can handle a variety of workpieces 1.

[0119] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments and their modifications include, for example, those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are equivalent.

[0120] For example, in the above embodiment, an inclined surface 6 is formed on the opening edge of the first opening 4 of the workpiece 1, and the guide surface 15a formed on the center portion 15 of the pressure member 16 is brought into surface contact over the entire circumference, but this is not limited to this case. For example, the inclined surface 6 does not need to be formed on the opening edge of the first opening 4 of the workpiece 1. Even in this case, by inserting the center portion 15 into the first opening 4 of the workpiece 1, the guide surface 15a can be in line contact with the opening edge of the first opening 4 of the workpiece 1 over the entire circumference. Therefore, even in this case, it is possible to suppress rotational runout of the workpiece 1, and similar operational effects can be achieved.

[0121] Furthermore, in the above embodiment, an example was given in which air was supplied between the pressure member 16 and the guide tube 130 using the supply mechanism 180, and the pressure member 16 was supported for rotation while floating in the air by air pressure, but the supply mechanism 180 is not essential and does not have to be provided. For example, the guide tube 130 may function as a sliding bearing, and the pressure member 16 may be rotationally supported with the outer peripheral surface of the pressure member 16 in slidable contact with the inner peripheral surface of the guide tube 130.

[0122] Furthermore, in the above embodiment, the pressure member 16 is rotated in conjunction with the rotation of the workpiece 1, that is, a so-called co-rotating configuration is used as an example, but the present invention is not limited to this. For example, a rotation mechanism may be provided to rotate the pressure member 16 around the central axis O1 of the workpiece 1, and with the center portion 15 inserted inside the first opening 4 of the workpiece 1, the pressure member 16 may be rotated using the rotation mechanism in synchronization with the rotation of the workpiece 1. Whether or not a rotation mechanism is required may be determined appropriately depending on, for example, the shape, size, etc. of the workpiece 1.

[0123] Furthermore, in the above embodiment, the supply mechanism 180 and the switching mechanism 190 have been described using air as an example of a fluid, but the fluid is not limited to air. For example, hydraulic pressure obtained by supplying oil may be used.

[0124] Furthermore, in the above embodiment, an example has been described in which a pair of lower roll 11 and upper roll 12 are used, which is a total of three rolls, but the present invention is not limited to this. For example, as shown in Fig. 15, a grinding machine 200 may be provided with a total of two rolls, one lower roll 11 and one upper roll 12. The grinding machine 200 in this case can also achieve the same effects as the grinding machine 10 of the above embodiment. In the case of this grinding machine 200, it is preferable to arrange the lower roll 11 and the upper roll 12 so that they are aligned vertically with the workpiece 1 therebetween, as shown in Fig. 15. This makes it easier to rotate the workpiece 1 stably at the processing position S by cooperating with the lower roll 11 and the upper roll 12.

[0125] Furthermore, in the above embodiment, an example was given of machining a two-stage cylindrical workpiece 1 having a small diameter portion 2 and a large diameter portion 3, but the shape of the workpiece 1 is not limited to this case. For example, as shown in Fig. 16, the grinding machine 10 can be suitably used for a long cylindrical workpiece 1 that is elongated in the left-right direction L1 and whose outer diameter does not change along its entire length. In this case, since the workpiece 1 is formed long in the left-right direction L1, the center of gravity G of the workpiece 1 itself is separated from the machining area (second opening 5) of the workpiece 1. Therefore, rotational runout and the like tend to occur easily during machining of the workpiece 1.

[0126] In this regard, according to the grinding machine 10 of this embodiment, the center portion 15 of the pressure member 16 is pressed against the first opening 4 of the workpiece 1 located on the opposite side of the processing area (second opening 5) where the grinding wheel 17 is set, and the pressure member 16 is inserted into the workpiece 1, so that rotational runout and the like can be effectively suppressed as in the above embodiment, even with a long workpiece 1. Therefore, even with this type of workpiece 1, the inner peripheral surface of the workpiece 1 can be ground while ensuring sufficient processing accuracy.

[0127] The present invention further includes the following aspects. <1> A grinding machine that grinds an inner peripheral surface of a cylindrical workpiece having a first opening and a second opening while rotating the workpiece about a central axis, A first rotating roll arranged above the workpiece arranged at a processing position so as to be able to contact the outer peripheral surface of the workpiece; a second rotating roll that is disposed below the workpiece so as to be able to contact the outer peripheral surface of the workpiece and that cooperates with the first rotating roll to rotate the workpiece around the central axis at the processing position; a shoe disposed along the central axis and slidably abutting against an outer peripheral surface of the workpiece to hold the workpiece at the processing position; a pressure member having a center portion that penetrates into the workpiece while contacting the opening edge of the first opening, The first rotating roll and the second rotating roll rotate the workpiece at the processing position with the second opening facing outward, the pressure member is rotatable around the central axis together with the workpiece while pressing the center portion against the workpiece along the central axis, The center portion has a guide surface that contacts the opening edge of the first opening over its entire circumference, thereby guiding the rotation of the workpiece so that it rotates around the central axis. <2> <1> In the grinding machine described in The guide surface is formed in a tapered shape centered on the central axis and is in contact with the opening edge of the first opening over the entire circumference. <3> <1> or <2> In the grinding machine described in a guide tube that surrounds the pressure member from the outside and accommodates the pressure member therein; The pressure member is supported by the guide tube so as to be rotatable around the central axis. <4> <3> In the grinding machine described in a supply mechanism for supplying a fluid between the pressure member and the guide tube, The pressure member is rotatably supported in a non-contact state relative to the guide tube by supplying a fluid. <5> <3> or <4> In the grinding machine described in a switching mechanism that switches the position of the pressure member between a pressing position where the center portion is pressed against the workpiece and a release position where the center portion is separated from the workpiece and released from the pressing by moving the pressure member along the central axis relative to the guide tube. <6> <1> from <5> In the grinding machine according to any one of the above items, The second rotating roll is provided as a pair and spaced apart along the central axis, The first rotating roll and the shoe are disposed along the central axis between the pair of second rotating rolls. <7> <6> In the grinding machine described in The workpiece is formed in a stepped shape having a plurality of different outer diameters, A grinding machine, wherein the pair of second rotating rolls are arranged to contact the outer peripheral surfaces of portions of the workpieces that have a common outer diameter. <8> <1> from <7> In the grinding machine according to any one of the above items, The first rotating roll, the second rotating roll, and the shoe are arranged closer to the second opening than the center of gravity of the workpiece. [Explanation of symbols]

[0128] O1: Central axis of workpiece P1: Pressing position P2…Release position G: Center of gravity of workpiece S…Processing position 1...Work 10, 200...Grinding machine 4...First opening of workpiece 5...Second opening of workpiece 12...Upper roll (first rotating roll) 11...Lower roll (second rotating roll) 13...Main shoe (shoe) 15...Center section 15a...Guide surface 16...Pressure member 130...Guide tube 180…supply mechanism 190...Switching mechanism

Claims

1. A grinding machine that grinds an inner peripheral surface of a cylindrical workpiece having a first opening and a second opening while rotating the workpiece about a central axis, a first rotating roll disposed above the workpiece disposed at a processing position so as to be able to contact the outer peripheral surface of the workpiece; a second rotating roll that is disposed below the workpiece so as to be able to contact the outer peripheral surface of the workpiece and that cooperates with the first rotating roll to rotate the workpiece around the central axis at the processing position; a shoe disposed along the central axis and slidably abutting against an outer peripheral surface of the workpiece to hold the workpiece at the processing position; a pressure member having a center portion that penetrates into the workpiece while contacting an opening edge of the first opening, The first rotating roll and the second rotating roll rotate the workpiece at the processing position with the second opening facing outward, the pressure member is rotatable around the central axis together with the workpiece while pressing the center portion against the workpiece along the central axis, The center portion has a guide surface that contacts the opening edge of the first opening over its entire circumference, thereby guiding the rotation of the workpiece so that it rotates around the central axis.

2. 2. The grinding machine according to claim 1, The guide surface is formed in a tapered shape centered on the central axis and is in contact with the opening edge of the first opening over the entire circumference.

3. 2. The grinding machine according to claim 1, a guide tube that surrounds the pressure member from the outside and accommodates the pressure member therein; The pressure member is supported by the guide tube so as to be rotatable around the central axis.

4. 4. The grinding machine according to claim 3, a supply mechanism for supplying a fluid between the pressure member and the guide tube, The pressure member is rotatably supported in a non-contact state relative to the guide tube by supplying a fluid.

5. 5. The grinding machine according to claim 3 or 4, a switching mechanism that switches the position of the pressure member between a pressing position where the center portion is pressed against the workpiece and a release position where the center portion is separated from the workpiece and released from the pressing by moving the pressure member along the central axis relative to the guide tube.

6. 2. The grinding machine according to claim 1, The second rotating roll is provided as a pair and spaced apart along the central axis, The first rotating roll and the shoe are disposed along the central axis between the pair of second rotating rolls.

7. 7. The grinding machine according to claim 6, The workpiece is formed in a stepped shape having a plurality of different outer diameters, A grinding machine, wherein the pair of second rotating rolls are arranged to contact the outer peripheral surfaces of portions of the workpieces that have a common outer diameter.

8. 2. The grinding machine according to claim 1, The first rotating roll, the second rotating roll, and the shoe are arranged closer to the second opening than the center of gravity of the workpiece.

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