JP7210307B2 - Method for manufacturing metal parts - Google Patents

Description

The present invention relates to a method for manufacturing metal parts and metal parts.

Accurate machining of dimensions, coaxiality between the outer diameter and inner diameter, squareness and parallelism of each surface, etc. for a perforated cylindrical metal member with concentric outer and inner diameters In this case, the order of machining each surface is specified based on the machining method, the configuration of the machining apparatus, and the like.

Patent Literature 1 discloses the following configuration for machining a workpiece having a first flat outer surface, a second flat outer surface, a hole, and a non-flat outer surface. According to DE 10 2005 020 000 A1, the grinding machine first clamps the workpiece on the workpiece headstock from the side of the second flat outer surface, and on one side of the workpiece the first flat outer surface and any non-flat outer surface. and the holes are configured to be ground. The bore and the first outer surface are then ground at least occasionally simultaneously, after which the workpiece is clamped by a clamping device in the bore. Thereafter, the clamping by the work headstock is released, so that the now released second flat outer surface can be ground in the same grinding machine by one of the grinding wheels of the first headstock. .

Japanese Patent Publication No. 2017-510468

When machining a cylindrical metal member having concentric outer and inner diameters, it is more difficult to obtain high precision with respect to the inner diameter than with respect to other surfaces. In particular, it is difficult to ensure high squareness of the surfaces of the inner diameter and outer diameter with respect to the end face and high coaxiality of the surface of the inner diameter with respect to the surface of the outer diameter.

SUMMARY OF THE INVENTION An object of the present invention is to realize high precision for each surface including an inner diameter portion in relation to a cylindrical metal member having concentric outer and inner diameter portions and a method for manufacturing the same.

The present invention for achieving the above object comprises an inner diameter polishing step for polishing the inner diameter portion of the work, and an outer diameter polishing step for performing centerless polishing on the outer diameter portion of the work whose inner diameter portion has been polished by the inner diameter polishing step. and an end surface polishing step of polishing the end surface of the workpiece whose outer diameter portion has been polished by the outer diameter polishing step.
More preferably, in the inner diameter polishing step, the inner diameter portion is polished by wire inner diameter polishing for polishing the inner diameter portion of the work using a wire.
More preferably, the inner diameter of the wire is polished in the inner diameter polishing step by applying abrasive slurry to the wire and sandwiching free abrasive grains between the wire and the inner diameter of the work to polish the inner diameter of the work.
More preferably, in the outer diameter polishing step, a core rod is passed through the inner diameter portion of the workpiece whose inner diameter portion has been polished in the inner diameter polishing step, and the outer diameter portion of each of the plurality of workpieces passed through the core rod is the same. Polishing is performed in the process of .
More preferably, in the end surface polishing step, the end surface of the work is polished with reference to the outer diameter portion of the work polished in the outer diameter polishing step.
Further, the present invention for achieving the above object is a metal part having an inner diameter portion, an outer diameter portion, and a longitudinal component in which the inner diameter portion and the outer diameter portion extend, wherein the inner diameter portion has a hole diameter of 0.1 mm. 3.5 mm, the surface roughness Rz of the inner surface is 1.6 μm or less, and the length direction component has a length of 3 times or more that of the inner diameter portion.

According to the present invention, a cylindrical metal member having concentric outer and inner diameter portions and a method for manufacturing the same can achieve high precision for each surface including the inner diameter portion.

It is a figure which shows the shape of the metal component (work) of the process object by the manufacturing method of this embodiment. 4 is a flow chart showing the procedure of polishing according to the present embodiment. It is a figure which shows the method of wire internal-diameter grinding|polishing. It is a diagram showing how the abrasive grains of the wire polish the inner diameter portion of the work, FIG. FIG. 4(C) is a diagram showing how chips (chips) are separated from the inner diameter portion. It is a figure which shows the schematic structure of a centerless grinder, FIG. 5(A) is a front view, FIG.5(B) is a top view. FIG. 6 is a view showing the essential parts of the centerless grinder of FIG. 5; It is a figure which shows the concept of through feed polishing. FIG. 8A is a diagram showing a configuration example of a centerless grinding machine for through-feed grinding, FIG. 8A is a diagram showing the arrangement (positional relationship) of a grinding wheel, a regulating wheel, and a blade, and FIG. 8B is an adjustment for a workpiece. FIG. 8(C) is a view showing an example of how the wheel hits the workpiece, and FIG. 8C is a view showing another example of how the adjustment wheel hits the workpiece. FIG. 4 is a diagram showing how a work having a core rod passed through a hole is ground. FIG. 2 is a view showing an end face polishing method by a two-roll one-shoe system, and is a view of the polishing device seen from the end face side of the workpiece to be polished. 11 is a top view of the polishing apparatus of FIG. 10; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<Workpiece to be processed>
FIG. 1 is a diagram showing the shape of a metal part (work) to be processed by the manufacturing method of the present embodiment. FIG. 1(A) is a perspective view, and FIG. 1(B) is a cross-sectional view taken along line Ib-Ib of FIG. 1(A). The workpiece 10 is a cylindrical member with a through hole, and has an inner diameter portion 11 that is the inner surface of the hole, an outer diameter portion 12 that is the outer peripheral surface, and end surfaces 13 and 14 . The workpiece 10 has a circular shape when viewed from the end surface 13 or 14 side, and the inner diameter portion 11 and the outer diameter portion 12 form concentric circles. That is, the end surfaces 13 and 14 are ring-shaped. Further, in the following description, the straight line connecting the centers of the rings of the end faces 13 and 14 may be called the central axis, and the length of the central axis between the end faces 13 and 14 may be called the length of the workpiece 10. In other words, the length of the workpiece 10 is the distance between the end faces 13 and 14, and is the value of the length component along which the inner diameter portion 11 and the outer diameter portion 12 extend. The shape of the work 10 shown in FIG. 1 is an example, and the shape of the work 10 to be processed according to this embodiment is not limited to that shown in FIG. For example, the workpiece 10 shown in FIG. is formed).

<Polishing procedure>
FIG. 2 is a flow chart showing the procedure of polishing according to this embodiment. In this embodiment, the first process performed on the workpiece 10 is the inner diameter polishing process (S201). In the inner diameter polishing step, the inner diameter portion 11 is polished by a method of processing without using other surfaces (the outer diameter portion 12 and the end surfaces 13 and 14) as a reference. By machining without setting a reference plane, the inner diameter part 11 can be machined with high accuracy without depending on the machining accuracy of the outer diameter part 12 and the end faces 13 and 14 . As an example of such a processing method, there is a method of polishing the inner diameter portion 11 using a metal wire (hereinafter referred to as wire inner diameter polishing). Specific contents of the inner diameter polishing step will be described later.

The next step performed on the workpiece 10 whose inner diameter portion 11 has been polished by the inner diameter polishing step is the outer diameter polishing step (S202). In the outer diameter polishing step, a core rod is passed through the hole of the workpiece 10 whose inner diameter portion 11 has been polished in the inner diameter polishing step (S201), and a plurality of workpieces 10 are aligned and subjected to centerless polishing to obtain the polished inner diameter portion 11. The polishing of the outer diameter portion 12 is performed on the basis of . By polishing the outer diameter portion 12 with the polished inner diameter portion 11 as a reference, coaxiality and parallelism between the outer diameter portion 12 and the inner diameter portion 11 can be achieved with high accuracy. Specific contents of the outer diameter polishing step will be described later.

The next step to be performed on the workpiece 10 whose outer diameter portion 12 has been polished by the outer diameter polishing step is the end surface polishing step (S203). In the end face polishing step, the end faces 13 and 14 are polished with the outer diameter portion 12 as a reference by holding the outer diameter portion 12 with two rollers and one shoe. By polishing the end surfaces 13 and 14 with the polished outer diameter portion 12 as a reference, the perpendicularity between the end surfaces 13 and 14 and the outer diameter portion 12 can be achieved with high accuracy. Further, along with this, the perpendicularity between the end surfaces 13 and 14 and the inner diameter portion 11 can be realized with high accuracy. Furthermore, parallelism between the end surfaces 13 and 14 can be realized with high accuracy. Specific contents of the end surface polishing step will be described later.

<Inner diameter polishing process>
In the inner diameter polishing step, the inner diameter portion 11 of the workpiece 10 is polished without using the outer diameter portion 12 and the end faces 13 and 14 as a reference. Here, wire inner diameter polishing using a metal wire will be described as an example of a specific method used in the inner diameter polishing process. Wire inner diameter polishing is polishing by a metal plastic deformation destruction mechanism using loose abrasive grains. In wire inner diameter polishing, a plurality of works 10 are connected and the inner diameter portions 11 of the plurality of works 10 can be polished in the same process.

FIG. 3 is a diagram showing a technique for polishing the inner diameter of a wire. As described above, in wire inner diameter polishing, a plurality of works 10 can be polished in the same process, but FIG. 3 shows how one work 10 is polished for the purpose of explaining the method. In wire inner diameter polishing, a wire 20 is passed through a hole in the work 10 . The wire 20 is coated with a slurry containing abrasive grains 21 (abrasive grain slurry). Therefore, by pressing the wire 20 against the inner diameter portion 11 of the work 10 and moving the wire 20 (or the work 10) so as to rub the inner diameter portion 11, the abrasive grains sandwiched between the wire 20 and the inner diameter portion 11 are removed. The inner diameter portion 11 is polished by 21 (loose abrasive grains). In the example shown in FIG. 3, the workpiece 10 is moved along the wire 20 while rotating the wire 20 (see the arrow in FIG. 3).

FIG. 4 is a diagram showing how the abrasive grains 21 of the wire 20 polish the inner diameter portion 11 of the work 10. As shown in FIG. FIG. 4A shows a state in which the abrasive grains 21 are in contact with the inner diameter portion 11, FIG. 4B shows a state in which the abrasive grains 21 scrape the surface of the inner diameter portion 11, and FIG. It is a figure which shows a mode that a chip (chip) separates from 11. FIG.

As shown in FIG. 4A, the wire 20 is pressed against the inner diameter portion 11 of the workpiece 10 with a pressure P, so that the abrasive grains 21 of the abrasive slurry applied to the wire 20 hit the surface of the inner diameter portion 11 and bite into it. . When one or both of the wire 20 and the workpiece 10 are moved in this state, the wire 20 and the surface of the inner diameter portion 11 move relatively. In the illustrated example, the wire 20 moves in the direction of the arrow M1, and the surface of the inner diameter portion 11 moves in the direction of the arrow M2.

Along with this movement, as shown in FIG. 4B, the abrasive grains 21 grind the surface of the inner diameter portion 11 to form scratch grooves (plastic deformation). As the movement of the wire 20 and the surface of the inner diameter portion 11 further progresses, the deformed portion caused by the formation of the scratch grooves shown in FIG. ) and separated from the inner diameter portion 11 .

Polishing of the inner diameter portion 11 of the workpiece 10 is performed as described above. According to the wire inner diameter polishing described above, since the inner diameter portion 11 is polished by the wire 20 passed through the hole of the work 10, a uniform pressure can be applied to the inner diameter portion 11 from one end to the other end of the work 10. For this reason, compared with the technique of holding the workpiece 10 by tightening one end face (for example, the end face 14) and inserting a whetstone with a shaft from the other end face (for example, the end face 13) to polish the inner diameter portion 11. Therefore, even if the workpiece 10 is long, the inner diameter portion 11 can be polished with high accuracy. Also, a plurality of works 10 can be connected and the inner diameter portions 11 of the plurality of works can be polished in the same process.

<Outer diameter polishing process>
In the outer diameter polishing step, the outer diameter portion 12 of the workpiece 10 is polished by centerless polishing. Specifically, a plurality of workpieces 10 are connected, a core rod is passed through a hole whose inner diameter has been ground, and centerless grinding is performed as a rod-shaped workpiece as a whole. Hereinafter, a centerless grinder used for centerless grinding will be described first, and then outer diameter grinding of a group of 10 rod-shaped workpieces will be described.

FIG. 5 is a diagram showing a schematic configuration of a centerless grinder. FIG. 5(A) is a front view, and FIG. 5(B) is a plan view. The centerless grinder 30 includes a base 31, a grinding wheel 32 and a grinding wheel support 33 provided on the base 31, a regulating wheel 34 and a regulating wheel support 35, a blade 36 and a blade support 37. . The workpiece 10 is positioned with its outer diameter portion 12 supported from three sides by a grinding wheel 32 , an adjustment wheel 34 and a blade 36 , and ground by the grinding wheel 32 .

The grinding wheel 32 is a cylindrical roller, and is supported by a grinding wheel support portion 33 so as to rotate about its axis. The grinding wheel support portion 33 supports and rotates the grinding wheel 32 . Further, the grinding wheel support portion 33 has a mechanism for advancing and retreating the grinding wheel 32 toward the blade 36 side (workpiece 10 side) (see the arrow in FIG. 5A).

The adjustment wheel 34 is a cylindrical roller and is supported by the adjustment wheel support portion 35 so as to rotate about its axis. The adjustment wheel support portion 35 supports and rotates the adjustment wheel 34 . In addition, the regulating wheel support section 35 has a mechanism for advancing or retracting the regulating wheel 34 toward the blade 36 side (workpiece 10 side) (see the arrow in FIG. 5A). Further, the adjustment wheel support section 35 has a mechanism for changing the orientation of the rotation shaft of the adjustment wheel 34 vertically or horizontally within a certain range (see arrows in FIG. 5A).

The blade 36 is an elongated plate-like pedestal having a constant width, and the upper surface thereof is used as an installation surface on which the workpiece 10 is installed. The installation surface is inclined toward the regulating wheel 34 side. Therefore, the workpiece 10 placed on the blade 36 tends to move toward the adjustment wheel 34 due to its own weight, and is supported by the adjustment wheel 34 . The blade support base 37 supports the blade 36 and has a mechanism for vertically retracting the blade 36 (see the arrow in FIG. 5A), so that the height when the workpiece 10 is installed can be adjusted. .

The axial direction of the workpiece 10 (that is, placed on the installation surface of the blade 36 ) during outer diameter grinding, the rotation axis of the grinding wheel 32 , and the longitudinal direction of the blade 36 are parallel. Hereinafter, this direction will be called a reference direction. Further, the rotating shaft of the regulating wheel 34 is substantially parallel to the reference direction, but as described with reference to FIG. Therefore, it may have a certain angle with respect to the reference direction. The spacing between the grinding wheel 32 and the adjustment wheel 34 is controlled by the grinding wheel support portion 33 and the adjustment wheel support portion 35 according to the size of the workpiece 10 . Also, the height of the blade 36 is controlled by the blade support 37 according to the size of the workpiece 10 .

FIG. 6 is a diagram showing the essential parts of the centerless grinder 30 of FIG. When the workpiece 10 is placed on the blade 36 , it is supported by the installation surface of the blade 36 and the adjustment wheel 34 and comes into contact with the grinding wheel 32 . When the grinding wheel 32 and the adjustment wheel 34 rotate in the same direction in this state, the work 10 is rotated in the opposite direction to the grinding wheel 32 and the adjustment wheel 34 and ground by the grinding wheel 32 . To explain the direction of rotation more specifically, the adjustment wheel 34 rotates upward at the position of contact with the work 10, and the grinding wheel 32 rotates downward at the position of contact with the work 10 (Fig. 6 arrows).

The main methods of polishing by the centerless polisher 30 are infeed polishing and through-feed polishing. In-feed polishing is a method of polishing while narrowing the distance between the grinding wheel 32 and the adjusting wheel 34 while the movement of the workpiece 10 in the reference direction is stopped. Specifically, for example, the grinding wheel 32 is advanced in a direction perpendicular to the reference direction, thereby narrowing the gap between the grinding wheel 32 and the adjusting wheel 34 to polish the workpiece 10 . In addition, by advancing not the grinding wheel 32 but the adjustment wheel 34 and the blade 36 (thus together with the workpiece 10 placed on the blade 36) in a direction perpendicular to the reference direction, the relationship between the grinding wheel 32 and the adjustment wheel 34 is increased. The workpiece 10 may be polished by narrowing the gap. Furthermore, depending on the type of workpiece 10, the direction of narrowing the gap between the grinding wheel 32 and the adjustment wheel 34 may not be the only option. The work 10 may be polished while changing the distance between the grinding wheel 32 and the adjusting wheel 34 by taking a complicated trajectory, including movement in a direction that changes the positional relationship with the work 10 . Through-feed polishing is a method of polishing while the gap between the grinding wheel 32 and the regulating wheel 34 is fixed and the work 10 is passed between them.

FIG. 7 is a diagram showing the concept of through-feed polishing. FIG. 7 shows a state in which through-feed polishing is performed on a group of workpieces 10, which are arranged in a row and each workpiece 10 is passed through a core rod 38 to form a rod-shaped assembly. In through-feed polishing, the workpieces 10 are polished by passing the group of workpieces 10 between the grinding wheel 32 and the adjustment wheel 34 while moving the workpieces 10 on the blade 36 along the reference direction. Therefore, as shown in FIG. 7, the gap between the grinding wheel 32 and the adjusting wheel 34 is arranged so as to gradually narrow along the direction in which the group of works 10 advances. Such an arrangement is realized, for example, by changing the orientation of the rotating shaft of the adjusting wheel 34 in the left-right direction by the adjusting wheel supporting portion 35 . When the group of works 10 advances along the arrow D between the grinding wheel 32 and the adjusting wheel 34 arranged in this way, the gap between the grinding wheel 32 and the adjusting wheel 34 gradually narrows, so that each work 10 moves. The outer diameter portion 12 of each work 10 is ground by being pressed against the grinding wheel 32 in order.

As shown in FIG. 7, by polishing a group of works 10 connected through the core rod 38, a plurality of works 10 can be continuously polished in the same process. At this time, at least several consecutive works 10 are polished at the same time.

FIG. 8 is a diagram showing a configuration example of a centerless polishing machine 30 for through-feed polishing. FIG. 8(A) is a diagram showing the arrangement (positional relationship) of the grinding wheel 32, the regulating wheel 34 and the blade 36, FIG. 8(B) is a diagram showing an example of how the regulating wheel 34 contacts the workpiece 10, C) is a diagram showing another example of how the regulating wheel 34 contacts the workpiece 10. FIG. When performing through-feed polishing, as shown in FIG. 8A, the rotating shaft of the regulating wheel 34 is tilted vertically with respect to the reference direction. Specifically, when performing polishing, the end on the side where the work 10 enters (the left side in FIG. 8A) is placed upward, and the end on the side where the work 10 exits (the right side in FIG. 8A). be tilted downwards. As described above, the regulating wheel 34 rotates upward at the contact position with the workpiece 10 . 8A (angle θ in the illustrated example), the rotating surface of the regulating wheel 34 is also tilted. Therefore, the rotation of the regulating wheel 34 generates a force that advances the workpiece 10 in the advancing direction. . As a result, when the workpiece 10 enters between the grinding wheel 32 and the adjustment wheel 34, it advances in the traveling direction as the adjustment wheel 34 rotates.

Here, how the regulating wheel 34 contacts the workpiece 10 will be described. When a cylindrical roller whose radius is constant over the entire length in the direction of the rotation axis is used as the adjustment wheel 34, when the rotation axis of the adjustment wheel 34 is tilted as described above, the line of contact with the work 10 on the adjustment wheel 34 is A component in the circumferential direction of the regulating wheel 34 will be included. Therefore, as shown in FIG. 8B, the line LC in contact with the workpiece 10 on the adjustment wheel 34 swells toward the workpiece 10 (radially outward from the rotation axis of the adjustment wheel 34). In this case, when the workpiece 10 advances between the grinding wheel 32 and the adjustment wheel 34, the strength of the force that the adjustment wheel 34 presses against the grinding wheel 32 changes depending on the position of the workpiece 10. FIG. With such a configuration, it is difficult to specify the appropriate arrangement of the regulating wheel 34 (the angle of the rotation shaft with respect to the reference direction and the distance from the grinding wheel 32) for performing the desired grinding of the workpiece 10. FIG.

Therefore, as shown in FIG. 8C, the regulating wheel 34 is deformed so that the line LC in contact with the workpiece 10 becomes a straight line with the rotating shaft of the regulating wheel 34 tilted. Specifically, the outer peripheral surface of the regulating wheel 34 is made to be a single-leaf hyperboloid of rotation. The deformation of the regulating wheel 34 is performed, for example, by grinding the outer peripheral surface of the regulating wheel 34 with a dresser. The one-leaf hyperboloid of rotation that makes the line LC in contact with the workpiece 10 on the adjustment wheel 34 a straight line varies depending on the angle of the rotation axis of the adjustment wheel 34 with respect to the reference direction (angle θ in FIG. 8A). Therefore, an appropriate angle .theta. is determined according to the size, shape, and material of the workpiece 10, the accuracy required in polishing, the working time, etc., and the necessary shape of the outer peripheral surface of the regulating wheel 34 is determined accordingly. will be molded individually.

FIG. 9 shows how the workpiece 10 with the core rod 38 passed through the hole is ground. 9 shows the work 10, grinding wheel 32, regulating wheel 34 and blade 36 shown in FIG. 7 viewed from the exit side of the work 10 (viewed in the opposite direction of arrow D shown in FIG. 7). . That is, in FIG. 9, the workpiece 10 advances from the back of the paper toward the front. In FIG. 9, the workpiece 10 after being ground (that is, after passing between the grinding wheel 32 and the regulating wheel 34) is shown in solid lines, and before being ground (that is, after passing between the grinding wheel 32 and the regulating wheel 34). The workpiece 10 (before passing between the regulating wheel 34) is shown in dashed lines. The difference between the workpiece 10 indicated by the dashed line and the workpiece 10 indicated by the solid line is the machining allowance removed by grinding the outer diameter.

In outer diameter grinding using the centerless grinder 30, when a group of works 10 connected through a core rod 38 are ground while being rotated by a grinding wheel 32 and a regulating wheel 34, each work 10 rotates around the core rod 38. do. This movement acts to maintain the core rod 38 at the center axis position of the inner diameter portion 11 . As a result, since the machining allowance portion of the outer diameter portion 12 is biased in the opposite direction to the eccentric direction, the coaxiality between the inner diameter portion 11 and the outer diameter portion 12 is corrected by grinding the machining allowance portion.

Polishing of the outer diameter portion 12 of the workpiece 10 is performed as described above. The core rod 38 used to form the group of rod-shaped works 10 is formed with a precision corresponding to the precision of the inner diameter portion 11 of the work 10 by, for example, centerless grinding. Therefore, by performing centerless polishing on the group of works 10 connected through the core rod 38, the outer diameter portion 12 is polished with the inner diameter portion 11 as a reference. Then, the coaxiality and parallelism of the inner diameter portion 11 and the outer diameter portion 12 can be achieved with high accuracy corresponding to the accuracy of the inner diameter portion 11 . Further, the outer diameter portions 12 of a plurality of works 10 connected through the core rod 38 can be polished in the same step.

<End surface polishing process>
In the end face polishing step, the end faces 13 and 14 are plunge-polished by a two-roll one-shoe method while rotating the workpiece 10 around the central axis. The end surfaces 13 and 14 are polished, for example, by applying a whetstone from one end surface while stopping the movement of the work 10 in the direction of the central axis.

FIG. 10 and FIG. 11 are diagrams showing the end surface polishing method by the two-roll one-shoe system. FIG. 10 is a view of the polishing apparatus viewed from the end surface of the work 10 to be polished. 11 is a top view of the polishing apparatus of FIG. 10. FIG. A polishing device 40 used for polishing the end faces includes rollers 41 and 42 , a shoe 43 , a stopper 44 , a grindstone 45 and a grindstone supporter 46 .

The interval between the two rollers 41 and 42 is adjusted according to the size of the workpiece 10. As shown in FIG. The shoe 43 is a pedestal on which the workpiece 10 is placed, and the upper surface of the shoe 43 is used as the installation surface of the workpiece 10 . The installation surface is inclined toward one roller side (the roller 42 side in the example shown in FIG. 10). Therefore, the workpiece 10 placed on the shoe 43 tends to move toward the roller 42 due to its own weight and is supported by the roller 42 . Also, one of the rollers 41 and 42 is arranged such that its rotation axis is parallel to the central axis direction of the workpiece 10 . The other of the rollers 41 and 42 is arranged such that its rotation axis is inclined at a constant angle with respect to the direction of the central axis of the workpiece 10 . Here, it is assumed that the rotation axis of the roller 41 is parallel to the central axis direction of the work 10 and the rotation axis of the roller 42 is inclined. The inclination of the rotating shaft of the roller 42 is such that the side of the stopper 44 is low and the side of the grindstone 45 is high. As a result, the rotation surface of the roller 42 is tilted, and a force is generated to advance the workpiece 10 toward the stopper 44 side. The work 10 has an outer diameter portion 12 supported from three sides by rollers 41 and 42 and a shoe 43 , rotates as the rollers 41 and 42 rotate, and is pressed against a stopper 44 by receiving the rotation of the roller 42 .

The stopper 44 contacts one end face of the work 10 supported by the rollers 41 and 42 and the shoe 43 to stop the movement of the work 10 in the central axis direction. As the stopper 44, either a freely movable wobble type or a standard fixed type is used according to the shape of the end surface of the workpiece 10. FIG.

The grindstone 45 is in contact with one end face of the work 10 that rotates while being supported by the rollers 41 and 42 and the shoe 43, and grinds the end face. The grindstone support portion 46 advances and retracts the grindstone 45 in a direction parallel to the central axis direction of the work 10 . Thereby, the grindstone support portion 46 realizes plunge grinding by pressing the grindstone 45 against the end surfaces 13 and 14 of the rotating work 10 .

As described above, the end surfaces 13 and 14 are polished with the outer diameter portion 12 as a reference. As a result, the perpendicularity of the end surfaces 13 and 14 to the outer diameter portion 12 can be achieved with high accuracy. Moreover, since the parallelism of the outer diameter portion 12 and the inner diameter portion 11 is achieved with high accuracy, the perpendicularity of the end surfaces 13 and 14 to the inner diameter portion 11 can also be achieved with high accuracy. Then, parallelism between the end surfaces 13 and 14 can be achieved with high accuracy.

<Processing Accuracy of Internal Diameter Polishing Process>
As a method for polishing the inner diameter portion 11 of the workpiece 10 having the shape shown in FIG. 1, in addition to the wire inner diameter polishing described with reference to FIGS. Specifically, one end face (eg, end face 14) of the work 10 is tightened to fix the work 10, and the inner diameter portion 11 is polished by inserting a whetstone with a shaft from the other end face (eg, end face 13) side. do. However, in such a method, if the length of the workpiece 10 is increased (the depth of the hole is increased) and the shaft of the mounted grindstone is lengthened in order to correspond to this, the shaft length increases as it goes deeper into the hole of the workpiece 10. Due to lack of rigidity, the grindstone escapes, and a situation arises in which the deep part of the hole cannot be machined well. Therefore, the diameter of the inner diameter portion 11 is likely to vary depending on the location (for example, the shape of the hole becomes tapered as it goes deeper). In addition, it is not easy to reduce the surface roughness beyond a certain level. Further, in order to obtain sufficient precision, it is necessary to frequently dress the grindstone, which lowers the operating rate of the apparatus and shortens the service life of the grindstone. With the miniaturization of parts (products), the inner diameter of the workpiece 10 tends to be smaller (the diameter of the inner diameter portion 11 is shorter), but the length tends to be longer. become.

The shaft-mounted grindstone has a structure in which the grindstone is placed around the shaft. It tends to vibrate sometimes. Therefore, the dimensional accuracy, roundness, and surface roughness of the workpiece 10 are deteriorated. It is conceivable to improve dimensional accuracy, roundness and surface roughness by processing with a very small machining allowance over a long period of time, but in this case, productivity is greatly reduced.

In addition, when the inner diameter of the work 10 becomes smaller, the grindstone placed on the shaft also needs to be thinner, so the life of the grindstone is shortened and replacement work is frequently performed, which also leads to a decrease in productivity. As a specific example, a case of polishing a workpiece 10 having an inner diameter portion 11 with a diameter of about 3.3 mm and a length of about 6 mm will be described. Here, it is assumed that polishing is performed so that the inner diameter portion 11 of the workpiece 10 has a surface roughness Rz of 1.6 μm or less. The numerical value of surface roughness Rz=1.6 μm is the roughness at the time of general finish machining in metal working. When processing is performed under such conditions, it is necessary to dress the grindstone every 100 times to 100-odd times of processing. In grinding with a grindstone with a shaft, a realistic workpiece 10 to be processed has a length up to about twice the diameter of the inner diameter portion 11 .

On the other hand, these are greatly improved by using the method of polishing the inner diameter of the wire. In the wire inner diameter polishing, since the inner diameter portion 11 is polished by the wire passed through the hole of the work 10, even if the length of the work 10 becomes long or the inner diameter becomes small, as in the case of the whetstone with a shaft, Insufficient rigidity of the shaft does not lead to deterioration of dimensional accuracy, roundness and surface roughness. Therefore, in the inner diameter polishing of the wire, even the workpiece 10 whose length is three times or more the diameter of the inner diameter portion 11 can be polished with the required dimensional accuracy, roundness, and surface roughness. can. In addition, when polishing the inner diameter of the wire, it is possible to suppress the deterioration of the sharpness by polishing while supplying abrasive slurry, so there is no need for frequent dressing and replacement of the grinding wheel as in the case of a mounted grinding wheel, which improves productivity. can suppress the decrease in

Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above embodiments. For example, in the outer diameter polishing step, the outer diameter portion may be polished with the inner diameter portion as a reference by centerless polishing, and the specific configuration of the polishing machine is not limited to the above-described embodiment. For example, in the above-described embodiment, the direction of the rotation axis of the adjustment wheel of the centerless grinder is changeable, but the direction of the rotation axis of the grinding wheel may also be changed. Further, in the end face polishing step, the end face may be polished with reference to the outer diameter portion, and the polishing method and the configuration of the polishing apparatus are not limited to the above-described embodiments. In addition, the present invention includes various modifications and alternative configurations that do not depart from the scope of the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 10... Work 11... Inner diameter part 12... Outer diameter part 13, 14... End face 20... Wire 21... Abrasive grain 30... Centerless grinder 31... Base 32... Grinding wheel 33... Grinding wheel Supporting portion 34 Adjusting wheel 35 Adjusting wheel support 36 Blade 37 Blade support 38 Core rod 40 Polishing device 41, 42 Roller 43 Shoe 44 Stopper 45 ... Grindstone, 46 ... Grindstone support part

Claims (4)

an inner diameter polishing step of polishing the inner diameter of the work;
an outer diameter polishing step of polishing the outer diameter portion of the work, the inner diameter portion of which has been polished by the inner diameter polishing step, by centerless through-feed polishing ;
an end surface polishing step of polishing an end surface of the work having the outer diameter portion polished by the outer diameter polishing step;
In the outer diameter polishing step, a core rod is passed through the inner diameter portion of the work whose inner diameter portion has been polished in the inner diameter polishing step, and each of the plurality of works passed through the core rod is not constrained to each other. A method of manufacturing a metal part, wherein the outer diameter portions of the plurality of workpieces are ground in the same step while being rotatable about a core rod. 2. The method of manufacturing a metal part according to claim 1, wherein said inner diameter polishing step polishes said inner diameter portion by wire inner diameter polishing for polishing said inner diameter portion of said workpiece using a wire. The inner diameter polishing of the wire in the inner diameter polishing step includes polishing the inner diameter portion of the work by applying abrasive slurry to the wire and sandwiching free abrasive grains between the wire and the inner diameter portion of the work. 3. The method of manufacturing a metal part according to claim 2. 2. The method of manufacturing a metal component according to claim 1, wherein said end face polishing step polishes said end face of said work with reference to said outer diameter portion of said work polished in said outer diameter polishing step.

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