JP5344941B2 - Crankshaft manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a crankshaft which machines with high precision an outer peripheral surface and a chamfer in a flange section, including a joint with the chamfer, and which improves the machining efficiency at that time without causing a high cost. <P>SOLUTION: In the turning step with respect to the O/S flange section 15 of a blank 10 of the crankshaft, the chamfer 19 having one or a plurality of tapered surfaces on a circumferential edge is formed by turning the circumferential edge of the flange section 15. In the grinding step of the O/S flange section 15, the outer peripheral surface 17 and an end surface 18 adjacent to the chamfer 19 in the O/S flange section 15, except for the region of the chamfer, are subjected to grinding. In the finishing step, the outer peripheral surface 17 and the tapered surface and the joint therebetween are polished by holding the O/S flange section 15 by clamp arms 41 and 42 which have a tubular pressing surface 46 corresponding to the outer peripheral surface 17, and tapered pressing surfaces 48 and 50 corresponding to the tapered surface, and by relatively sliding them while pressing a polishing film 43. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a crankshaft.

  On the rear side of the crankshaft, for example, there is an oil seal mounting flange portion (hereinafter simply referred to as an O / S flange portion) for mounting an annular oil seal so that lubricating oil in the engine does not leak to the outside. An annular oil seal is fitted to the outer peripheral surface of the flange portion with a slight tightening allowance to seal the inside of the engine that accommodates most of the crankshaft.

  At this time, an appropriate chamfering process is performed on the rear peripheral edge of the O / S flange portion so that, for example, a rubber oil seal is smoothly introduced into the outer peripheral surface of the flange. As an example, Patent Document 1 below discloses that a chamfered portion having a tapered surface is formed on the rear side periphery of an O / S flange portion provided at a rear side end portion of a crankshaft.

  On the other hand, the joint between the taper surface of the chamfered portion and the outer peripheral surface of the O / S flange portion connected to the taper surface on the front side allows the oil seal to be closely attached to the outer peripheral surface of the O / S flange portion. In order to ensure a good sealing performance, it is desirable that there is no burr or the like and the connection is smooth. Therefore, the outer peripheral surface and the tapered surface of the flange portion including the joint are required to have excellent surface roughness and be smooth.

JP 2008-303938 A

  Here, considering the above requirements and the fact that the rear side end surface of the flange portion for O / S is usually the contact surface (mounting surface) of the flywheel, the outer peripheral surface and the chamfered portion of the flange portion, and the rear side end surface It is conceivable to perform rough turning in advance, and then perform grinding finishing at once with a general-purpose grindstone integrally having a grinding surface corresponding to these surfaces.

  Specifically, first, in the rough turning process, a flywheel mounting flange portion (hereinafter simply referred to as F / W) located on the rear side end surface from the outer peripheral surface of the O / S flange portion and further to the rear side of the O / S flange portion. The part reaching the outer peripheral surface of the flange portion is turned so as to have an appropriate surface roughness. Then, as shown in FIG. 8, in the rear portion grinding step, the grinding surface 101 having a shape corresponding to the outer peripheral surface 117 of the O / S flange portion 115, the grinding surface 102 having a shape corresponding to the rear side end surface 118, and the chamfering are provided. The flange portion 115 is ground using a grinding wheel 100 having a grinding surface 103 having a shape corresponding to the portion 119. In this illustrated example, the outer peripheral surface 117 of the O / S flange 115 and the rear surface are rearranged by pressing the overall grinding wheel 100 with the rotation shaft inclined to approach the O / S flange 115 from obliquely above. The side end face 118 and the chamfered portion 119 are finished simultaneously by one grinding process.

  However, the above-described method requires processing into a special shape for the general-purpose grindstone 100 in accordance with a complicated grindstone shape. Therefore, it cannot be said that the durability is so excellent in consideration of workability. A normal grindstone will be used. For this reason, it is necessary to carry out a frequent review (so-called truing), which causes a reduction in equipment operation rate and hence processing efficiency.

  Further, an operation is performed in which the rotary shaft of the overall grinding wheel 100 is set obliquely with respect to the rotational shaft of the workpiece (crankshaft), and the overall grinding stone 100 is approached obliquely and pressed against the crankshaft. This requires a dedicated grinding machine that is separate from other parts of the crankshaft (such as crankpins and journals). This leads to an increase in the number of equipment and equipment costs, and also leads to an increase in man-hours.

  Of course, the above-described problem is not limited to the O / S flange portion, but may also occur in the same manner with respect to a flange portion in which another member may be fitted.

  In view of the above circumstances, in the present specification, the outer peripheral surface and the chamfered portion of the flange portion including the joint with the chamfered portion can be processed with high accuracy, and the processing efficiency at that time is improved without causing an increase in cost. It is a technical problem to be solved by the present invention to provide a method of manufacturing a crankshaft that can be used.

The present invention has been made to solve the above problems. That is, the crankshaft manufacturing method according to the present invention includes a turning step of turning at least a predetermined flange portion and a pin portion, and a journal portion of the rough shape material of the crankshaft, a flange portion and a pin portion, And grinding process to grind the journal part with a grindstone , and polish the flange part , the pin part, and the journal part by pressing the polishing film against the flange part and the pin part and relatively sliding the journal part. A crankshaft manufacturing method including a finishing process to be performed, and in the turning process, a chamfered portion having one or a plurality of tapered surfaces is formed on the peripheral edge by performing a turning process on the peripheral edge of the flange part. Remove the chamfered portion of the flange and apply grinding to the outer peripheral surface and end surface adjacent to this area. The outer peripheral surface, the tapered surface, and the joint between them are polished by sandwiching the flange portion with a clamp member having a cylindrical pressing surface and a tapered pressing surface corresponding to the tapered surface and pressing the polishing film. Characterized by the points

  As described above, in the manufacturing method according to the present invention, the outer peripheral surface of the flange portion and the tapered surface of the chamfered portion and the joints thereof are polished integrally with the polishing film. Even when burrs occur at the joints between the surfaces, they can be removed, and these surfaces can be finished with high accuracy and smoothness. In addition, the series of processing from chamfered part formation to finishing is performed by combining grinding and turning with a finishing film, so that the outer peripheral surface of the flange part and the end face on the rear side are removed. It is not necessary to use a complex shaped grinding wheel for grinding. Rather, it is possible to perform grinding efficiently by using a grindstone (grinding machine) used for grinding crank pins, crank journals, and the like. In addition, since a grindstone having a simple shape can be used for grinding the outer peripheral surface and end face, it is possible to employ a grindstone having excellent durability and polishing performance such as a CBN grindstone without being restricted by the material. it can. Thereby, the space | interval of a truing can be taken long and an equipment mobilization rate and by extension processing efficiency can be improved.

  In addition to the joints, the finish polishing is applied to the outer peripheral surface that requires high surface accuracy, so high-precision finishing in both regions can be performed without increasing the number of man-hours. . Furthermore, since it is not necessary to use dedicated grinding equipment such as a general-purpose grindstone or an angular grinding machine, the processing equipment can be simplified and the equipment cost can be reduced.

  Further, in the above manufacturing method, the chamfered portion has a plurality of tapered surfaces, and the clamp member has a plurality of shoes having a cylindrical pressing surface, and a tapered shape that is movable with respect to the shoes and corresponds to each tapered surface. A plurality of movable shoes each having a pressing surface, and by pressing a polishing film from a plurality of circumferential positions with a plurality of movable shoes, all taper surfaces can be polished. .

  When the chamfered portion has a plurality of tapered surfaces, for example, if a shoe integrally having a tapered pressing surface having a shape corresponding to the plurality of tapered surfaces in addition to the cylindrical pressing surface corresponding to the outer peripheral surface of the flange portion is used, the outer periphery It seems that a chamfered portion consisting of a surface and a plurality of tapered surfaces can be polished. However, since the polishing film basically has a flat shape in the width direction, with the shoe having the above shape, before firmly holding the polishing film between the flange portion and the shoe (the cylindrical pressing surface), The tapered pressing surface comes into contact with the end of the polishing film. In this case, the end of the polishing film cannot be bent into an appropriate shape, in other words, a shape corresponding to the outer peripheral surface, the chamfered portion, and the joint shape thereof, and thus it is difficult to perform appropriate polishing. Also, even if the polishing film is pushed and bent by the multi-step tapered pressing surface provided on the shoe, the thickness and material of the polishing film are limited to some extent, so that the complicated and minute multi-step tapered surface shape can be accurately followed. It is difficult to transform. On the other hand, according to the above method, the movable shoe can be pressed against the polishing film at a different timing from the shoe, so that it can be moved to the polishing film held between the shoe and the outer peripheral surface of the flange portion. By pressing the shoe, the polishing film can be pushed and bent to follow the tapered surface to be polished. Further, since the polishing film is pushed in from a plurality of circumferential positions by the plurality of movable shoes, it is only necessary to push and bend the end portion of the polishing film into a shape following only one tapered pressing surface. As a result, even when a chamfered portion having a plurality of tapered surfaces is provided on the periphery of the flange portion, the polishing film is forcedly bent into a shape following the chamfered portion, and the corresponding plurality of tapered surfaces are simultaneously polished. can do. Further, the joint between the tapered surface and the outer peripheral surface and the joint between the tapered surfaces can be finished smoothly.

  In addition, depending on the rigidity (bending characteristics) of the polishing film, it can be used at the joint between the outer peripheral surface and the tapered surface, which requires more precision, because the polishing film requires only a small bending angle. A partial region of the polishing film to be made can be a smooth curved surface, and a joint polished by this curved surface can be finished in a good state.

  When the movable shoe is used, a polishing film having a belt shape is supplied to the periphery of the flange portion, and the polishing film can be fed to one side in the longitudinal direction. You may make it arrange | position the movable shoe corresponding to the taper surface adjacent to an outer peripheral surface in the most upstream of the feed direction of a polishing film.

  With this type of polishing process, each time the workpiece is replaced, the polishing film is fed by a predetermined amount, so that the pressing portion (polishing portion) of the polishing film by the movable shoe is shifted little by little along its longitudinal direction. . Therefore, as described above, the movable shoe corresponding to the taper surface adjacent to the outer peripheral surface is preferentially arranged on the upstream side in the feed direction of the polishing film, so that the taper surface requiring more accuracy is always in a new state ( It can be polished with a polishing film in a good state. Further, it is possible to always perform a good polishing process on the joint between the outer peripheral surface and the tapered surface.

  As described above, according to the present invention, the outer peripheral surface of the flange and the chamfered portion including the joint with the chamfered portion can be processed with high accuracy, and the processing efficiency at that time can be improved without causing an increase in cost. It is possible to provide a method for manufacturing a crankshaft that can be used.

It is a flowchart corresponding to one Embodiment of the manufacturing method of the crankshaft which concerns on this invention. It is a front view of the crankshaft used as a process target. It is an enlarged front view of the rear side end of the crankshaft. It is an enlarged view of the chamfered part of the flange part for O / S. It is a principal part front view of the lapping apparatus which concerns on a finishing process. It is AA sectional drawing of the lap | wrap apparatus shown in FIG. It is the figure which expanded the chamfering part periphery of FIG. It is a figure for demonstrating notionally the method of grinding a chamfering part using a general-purpose grindstone.

  Hereinafter, an embodiment of a method for manufacturing a crankshaft according to the present invention will be described with reference to FIGS. In this embodiment, a case where a crankshaft for three cylinders is manufactured will be described as an example.

  FIG. 1 shows a flowchart corresponding to one embodiment of the manufacturing method. As shown in this flowchart, the crankshaft manufacturing method according to the present invention mainly includes (A) a rough shape material forming step of the crankshaft, and (B) a turning step of turning the rough shape material after forming. (C) drilling step, (D) grinding step, and (E) finishing step. In this embodiment, in (B) the turning step, a chamfered portion having a predetermined shape is formed on the rear side periphery of the O / S flange portion, and (D) in the grinding step, the chamfered portion is removed. The outer peripheral surface and end surface of the flange portion adjacent to the chamfered portion are ground. Further, in the (E) finishing step, the chamfered portion, the outer peripheral surface, and the joint between them are polished using a polishing film. Hereinafter, details of each process will be described.

(A) Rough Shape Forming Step First, the rough shape of the crankshaft to be subjected to the above-described series of processing is formed by a method such as forging or casting. In the case of forming by forging, an unprocessed surface called a so-called black skin remains on the surface of the rough shaped material.

(B) Turning Step Next, the rough shaped material formed in the step (A) is turned. Specifically, the black portion of the rough shape member 10 is obtained by turning the pin portion 11, the journal portion 12, the front portion 13, the rear portion 14 and the like of the rough shape member (crank journal) 10 shown in FIG. The shape and surface roughness of the black skin removal portion are finished to a predetermined accuracy (temporary finishing). The rear portion 14 mainly includes an O / S flange portion 15 for attaching an oil seal (not shown) and an F / W flange portion 16 for attaching a flywheel (not shown). In this turning process, in addition to the outer peripheral surface 17 and the rear-side end surface 18 of the O / S flange portion 15, a chamfered portion 19 made up of a plurality of tapered surfaces is provided on the peripheral edge on the rear side on the oil seal introduction side. They are formed (see FIG. 3 described later).

Specifically, as shown in FIG. 3, the chamfered portion 19 has an outer periphery of the O / S flange portion 15 in order to smoothly and accurately fit the outer peripheral surface 17 with a slight press-fitting of the oil seal. A first taper surface 20 inclined by a predetermined angle θ _{1 with} respect to the surface 17 is smoothly connected to the outer peripheral surface 17, and a second taper inclined with a predetermined angle θ ₂ (θ ₂ is larger than θ ₁ ) with respect to the outer peripheral surface 17. The surface 21 is smoothly connected to the first taper surface 20, and the third taper surface 22 inclined by a predetermined angle θ _{3 with} respect to the rear side end surface 18 of the O / S flange portion 15 is the rear side end surface 18 and the second taper. Each of the surfaces 21 has a smoothly connected shape. Here, a case where θ ₁ = 15 °, θ ₂ = 30 °, and θ ₃ = 15 ° can be exemplified as the inclination angles of the respective tapered surfaces 20 to 22. In the turning process, the tapered surfaces 20 to 22 constituting the chamfered portion 19 are formed, and a joint 23a having a predetermined diameter R is formed by turning between the first tapered surface 20 and the outer peripheral surface 17. The Similarly, joints 23b and 23c having a predetermined diameter R are also formed by turning between the first taper surface 20 and the second taper surface 21 and between the second taper surface 21 and the third taper surface 22. The At this time, the same surface as that when grinding is performed by adjusting the feed rate at the time of turning of the chamfered portion 19 to be lower than the feed rate at other portions other than the chamfered portion 19. Roughness (for example, surface roughness Ra is 10 μm or less) is realized.

(C) Drilling step After the turning process for the rough shape member 10 is completed as described above, the predetermined part such as the rear part 14, the front part 13, the pin part 11, etc. is subjected to a cutting process with a drill. Form oil holes, flywheel mounting holes, etc. at the locations.

(D) Grinding step Subsequently, the pin part 11, the journal part 12, the thrust part 24, the front part 13 and the rear part 14 (O / S flange part 15 and F / W flange part 16) of the rough profile 10 Each part is ground. Below, the case where grinding is performed in the order of (D1) to (D4) will be described.

(D1) Pin part grinding process First, a predetermined grinding process is performed with respect to the pin part 11 of the rough shaped member 10. In this case, as the grinding wheel for grinding the outer peripheral surface of the pin portion 11, for example, as shown in FIG. 4, a grindstone 26 having a simple shape in which the outer peripheral surface 25 becomes a grinding surface can be used.

(D2) Thrust Portion / F / W Flange Grinding Step Next, a predetermined grinding process is performed on the thrust portion 24 (thrust receiving surface) adjacent to the predetermined journal portion 12 of the rough profile 10. Further, the rear end surface 18 of the O / S flange portion 15 and the outer peripheral surface 27 of the F / W flange portion 16 located further on the rear side of the rear side end surface 18 are both a flywheel mounting surface (contact surface). Therefore, in order to secure a required squareness between the rear side end face 18 and the outer peripheral face 27 of the F / W flange portion 16, for example, as shown in FIG. It is desirable to grind the rear side end surface 18 and the outer peripheral surface 27 simultaneously using a grindstone 30 having an abrasive surface 28 and an outer peripheral surface 29. Further, it is also possible to grind the thrust portion 24 adjacent to the journal portion 12 with the front side end face 28 (and the rear side end face) using the grindstone 30.

(D3) Journal part grinding process Moreover, predetermined | prescribed grinding process is given with respect to the journal part 12 of the rough shape material 10. FIG. As shown in FIG. 4, a grindstone 26 having a simple shape in which the outer circumferential surface 25 is a grinding surface can be used for grinding the outer circumferential surface of the journal portion 12.

(D4) Front part / O / S flange part grinding step Subsequently, the front part 13 and the O / S flange part 15 of the rough profile 10 are subjected to predetermined grinding. In this case, for grinding the front portion 13 and the O / S flange portion 15, as in the grinding of the pin portion 11 and the journal portion 12, the grindstone 26 whose outer peripheral surface 25 shown in FIG. it can. Therefore, the same grindstone 26 can be used for the outer peripheral surface grinding of the front portion 13 and the outer peripheral surface grinding of the O / S flange portion 15.

  As described above, the outer peripheral surface of the F / W flange portion 16 as the pin portion 11, the journal portion 12, the thrust portion 24 adjacent to the predetermined journal portion 12, the front portion 13, and the rear portion 14 is ground. And finished to the required surface roughness. Further, with respect to the O / S flange portion 15, the chamfered portion 19 provided on the peripheral edge of the rear side is removed, and the outer peripheral surface 17 and the rear side end surface 18 adjacent to the chamfered portion 19 are subjected to grinding processing. The surface is finished to the required surface roughness. Further, in this case, since all the grinding surfaces need only be managed with coaxiality and squareness, all grinding can be performed with only the two types of grindstones 26 and 30 shown in FIG. Thereby, the freedom degree regarding the combination of a grinding location or a grinding procedure can be raised, and the improvement of grinding efficiency can be aimed at.

(E) Finishing step A polishing finishing process using a polishing film is performed on a predetermined portion of the rough shape member 10 obtained through the above steps (A) to (D). Specifically, as shown in FIG. 4, required polishing is performed on the outer peripheral surface 17 that becomes the seal mounting surface of the O / S flange portion 15 and the first tapered surface 20 that is connected to the outer peripheral surface 17 on the rear side. Processing (lapping) is performed to finish the both surfaces 17, 20 and their joints 23a more smoothly. Hereinafter, in addition to the outer peripheral surface 17 and the first tapered surface 20, a case where the same polishing process is applied to the second tapered surface 21 connected to the first tapered surface 20 and the rear side will be described as an example.

  FIG. 5 shows a front view of the main part of the lapping apparatus 40 used in the finishing process. The lap device 40 sandwiches the O / S flange portion 15 of the rough member 10 as a workpiece with a pair of clamp arms 41 and 42 as clamp members, and also clamps the clamp arms 41 and 42 and the O / S flange portion. The outer peripheral surface of the O / S flange portion 15 is provided with relative sliding between the polishing film 43 and the O / S flange portion 15 with the polishing film 43 interposed therebetween. 17 is polished. Here, the pair of clamp arms 41 and 42 is driven by a cylinder (not shown) provided on the base end side (right side in FIG. 5), thereby leading the ends of both clamp arms 41 and 42 (FIG. 5). The middle left side is moved close to and away from each other to perform an opening / closing operation (FIG. 5 is in a closed state).

  Concave surfaces 44, 45 for holding the O / S flange portion 15 to be polished are provided on the opposing surfaces of the clamp arms 41, 42, respectively. A plurality of shoes 47 having a cylindrical pressing surface 46 having a shape corresponding to the outer peripheral surface 17 of the flange portion 15 are provided. In addition, the one concave portion 44 can be independently driven separately from the shoe 47 and is a tapered surface constituting the chamfered portion 19 of the O / S flange portion 15, here the first tapered surface 20 adjacent to the outer peripheral surface 17. A first movable shoe 49 having a first tapered pressing surface 48 having a shape corresponding to (see FIG. 4) is provided. Further, in this illustrated example, the other concave portion 45 can be independently driven separately from the shoe 47 and corresponds to the second tapered surface 21 (see FIG. 4) adjacent to the first tapered surface 20 on the rear side. A second movable shoe 51 having a second tapered pressing surface 50 is provided. In the illustrated example, three shoes 47 are disposed at positions that are equally spaced in the circumferential direction in one of the recesses 44 and the other recess 45. Further, as shown in FIGS. 5 and 6, a first movable shoe 49 is disposed on the rear side of the shoe 47 provided at the substantially center in the circumferential direction of one recess 44, and the circumference of the other recess 45 is A second movable shoe 51 is disposed on the rear side of the shoe 47 provided substantially in the center in the direction. These movable shoes 49 and 51 are all disposed at positions facing the corresponding shoes 47, and these movable shoes 49 and 51 can be driven along a common virtual axis.

  The polishing film 43 is fed between the opposing surfaces of the pair of clamp arms 41 and 42 by an appropriate film supply means (not shown) provided in the lap device 40. In this embodiment, the polishing film 43 fed from the film supply means provided on the one clamp arm 41 side passes through one concave portion 44 via the film guide 52 provided near the tip of the one clamp arm 41. Then, it is folded back by the film guide 53 provided on the arm base end side, and further passes through the other recess 45 from the arm base end side to the tip end side, and through the film guide 54 provided in the vicinity of the tip end of the other clamp arm 42. Are sequentially sent to a film collecting section (not shown) provided on the other clamp arm 42 side. At this time, the polishing film 43 is fed so that the polishing surface on which the abrasive grains are arranged faces each other. As a result, the belt-like polishing film 43 is supplied around the O / S flange portion 15 sandwiched between the clamp arms 41 and 42 and the polishing surface is supplied toward the outer peripheral surface 17 of the O / S flange portion 15. It has come to be.

  Therefore, in this case, the first movable shoe 49 having the first tapered pressing surface 48 corresponding to the first tapered surface 20 adjacent to the outer peripheral surface 17 of the O / S flange portion 15 is compared with the second movable shoe 51. The polishing film 43 is arranged upstream of the feeding direction.

  Hereinafter, a case where polishing is performed using the lapping apparatus 40 configured as described above will be described. First, the clamp arms 41 and 42 with one end opened are relatively moved to a position where the O / S flange portion 15 of the rough profile 10 to be processed can be clamped, and then the clamp arms 41 and 42 are closed. Then, the O / S flange 15 is sandwiched between the clamp arms 41 and 42 via the polishing film 43 and the polishing surface of the polishing film 43 is pushed against the outer peripheral surface 17 by the cylindrical pressing surface 46 of each shoe 47. Hit it. Then, from this state, the crankshaft rough shape member 10 previously supported around the rotation shaft is rotated, and the polishing film 43 is slid in the circumferential direction with respect to the outer peripheral surface 17 of the O / S flange portion 15. By moving, the outer peripheral surface 17 is polished and finished to a predetermined surface roughness.

  Further, in a state in which the rough shaped member 10 is clamped by the clamp arms 41 and 42, the first movable shoe 49 provided in one of the concave portions 44 is moved toward the O / S flange portion 15, whereby FIG. ), The polishing film 43 is pushed and bent by the first tapered pressing surface 48 provided at the tip of the first movable shoe 49, and the bending portion 43 a of this film is made to follow the first tapered surface 20. Press. Therefore, by rotating the rough shaped member 10 from this state, the first tapered surface 20 is caused to slide in the circumferential direction with respect to the first tapered surface 20 of the chamfered portion 19 by pushing and bending the portion 43a of the polishing film 43. Is polished to a predetermined surface roughness. Further, as described above, a part of the rear side of the polishing film 43 is partially pushed and bent in the circumferential direction, so that the non-pressing portion of the polishing film 43 (the cylindrical pressing surface 46 of the shoe 47). And a portion between the first movable shoe 49 and the first tapered pressing surface 48) are smoothly curved and pressed against the joint 23a between the outer peripheral surface 17 and the first tapered surface 20. As a result, the joint 23a can be polished with the polishing film 43 and finished smoothly.

  At the same time as the polishing operation, the second movable shoe 51 provided in the other concave portion 45 (clamp arm 42) is moved toward the O / S flange portion 15 as shown in FIG. 7B. Then, the polishing film 43 is pressed and bent by the second tapered pressing surface 50 provided at the tip of the second movable shoe 51, and the pressing and bending portion 43 b of the film is pressed following the second tapered surface 21. Therefore, the rough shape member 10 is rotated from this state, and the second tapered surface 21 is slid in the circumferential direction with respect to the second tapered surface 21 of the chamfered portion 19 by sliding the pushing and bending portion 43 b of the polishing film 43. Is polished to a predetermined surface roughness. Further, as described above, a part of the rear side of the polishing film 43 is partially pushed and bent in the circumferential direction, so that the non-pressing portion of the polishing film 43 (the cylindrical pressing surface 46 of the shoe 47). And the second taper-shaped pressing surface 50 of the second movable shoe 51) are smoothly curved so that the joint 23a or the first taper surface 20 and the second taper surface between the outer peripheral surface 17 and the first taper surface 20 are curved. 21 is pressed against the joint 23b. Accordingly, both the joints 23a and 23b (at least the joint 23b between the first and second tapered surfaces 20 and 21) can be polished with the polishing film 43 to be finished smoothly.

  Further, if the tapered pressing surfaces 48 and 50 are provided on the movable shoes 49 and 51 as described above, the timing of pressing the polishing film 43 can be shifted between the outer peripheral surface 17 and the chamfered portion 19. In addition, the pressing force can be adjusted. That is, when the polishing film 43 is pressed against the tapered surfaces 20 and 21 of the chamfered portion 19 with the same pressing force as that of the shoe 47, the shape formed by turning may be deformed. However, by using the movable shoes 49 and 51, the polishing film 43 can be pressed with a force different from the pressing force (clamping force) of the shoe 47 on the fixed side, more precisely with a force smaller than this pressing force. Thereby, it is possible to improve the surface roughness and smoothly finish the surface without breaking the shape of the chamfered portion 19 formed by turning. Further, the tip portions of the movable shoes 49 and 51 are made of a softer material than the shoe 47 on the fixed side in order to make the tapered pressing surfaces 48 and 50 follow the shape of the chamfered portion 19 in a pressed state. In this case as well, wear of the tapered pressing surfaces 48 and 50 can be suppressed by adjusting the driving force (pressing force) of the movable shoes 49 and 51. Note that the means for adjusting the pressing force of the movable shoes 49 and 51 is arbitrary. For example, as shown in FIG. 6, a constant pressing force is applied using an elastic member such as a spring (adjusting the spring force). It is possible.

  By polishing as described above, in addition to the outer peripheral surface 17, the first tapered surface 20, and the second tapered surface 21 of the O / S flange portion 15, the joint 23 a between the outer peripheral surface 17 and the first tapered surface 20. The joint 23b between the first tapered surface 20 and the second tapered surface 21 is polished to a required surface roughness according to the abrasive grain roughness of the polishing film 43. And after completion | finish of grinding | polishing processing (finishing process), while opening the clamp arms 41 and 42 and taking out the grind | polished workpiece | work (rough shape material 10), the film 43 for grinding | polishing by a predetermined amount is wound up from the film collection | recovery part side. As a result, the polishing film 43 supplied to the insides of both the concave portions 44 and 45 is sent out in a downstream direction (direction indicated by a thick arrow in FIG. 5) by a corresponding amount, and a new workpiece (coarse shaped material) 10).

  Further, in this embodiment, the first tapered pressing surface 48 (first taper surface) corresponding to the first tapered surface 20 having a relatively small inclination angle on the one concave portion 44 side that is the upstream side in the feed direction of the polishing film 43. 1 movable shoe 49) and a second tapered pressing surface 50 (second movable shoe) corresponding to the second tapered surface 21 having a relatively large inclination angle on the other concave portion 45 side on the downstream side. 51). Therefore, by sending the polishing film 43 as described above, the polishing film 43 in a new state (the bending portion 43a thereof) is formed between the first tapered pressing surface 48 and the first tapered surface 20 located on the upstream side. Thus, the first tapered surface 20 and the joint 23a between the tapered surface 20 and the outer peripheral surface 17 can be finished with high accuracy. In particular, when the target of final polishing is the flange portion 15 for O / S, the finish of the joint 23a with the first taper surface 20 and the outer peripheral surface 17 leads to the adhesion of the oil seal and thus the oil tightness. Can be improved with high precision (for example, Ra is 0.5 μm or less), thereby improving the sealing performance.

  As described above, with respect to the rough shaped material 10 having a predetermined portion subjected to finish polishing, rotation balance measurement inspection, unbalance correction, pin portion 11 and journal portion 12 finish polishing processing, etc. are performed as necessary. By performing, a finished crankshaft is obtained.

  As mentioned above, although one Embodiment of this invention was described, this invention is not necessarily limited to the said exemplary method, Of course, it can take arbitrary forms within the scope of the present invention.

  The movable shoes 49, 51 may be one or more than three, and the arrangement relationship (including the arrangement relationship with the fixed shoe 47) is not limited to the above-described form.

  In the above-described embodiment, two types of movable shoes 49 and 51 (two types of tapered pressing surfaces 48 and 50) corresponding to both the first and second tapered surfaces 20 and 21 are provided and polished. As long as the first tapered surface 20 closest to (adjacent to) the outer peripheral surface 17 and the joint 23a between the tapered surface 20 and the outer peripheral surface 17 are smoothly polished by the polishing film 43, the other taper surfaces The presence or absence of polishing does not matter. The same applies to the joint between the tapered surfaces.

  Further, in the present invention, since the grinding process by the special-shaped total shape grindstone is eliminated, the degree of freedom of the combination of grinding of each part of the rough shaped material 10 is high, and the grinding order in the grinding process (D) is high. Therefore, various grinding modes can be employed without being bound by the above embodiment.

  Further, the object to be polished of the chamfered portion 19 is not limited to the O / S flange portion 15, and the present invention can be applied as long as the chamfered portion 19 needs to be finished with high accuracy. is there. More specifically, for example, not only the O / S flange portion 15 to which the oil seal is fitted, but also the first journal portion (the journal portion 12 closest to the front portion 13) to which the angle plate is fitted, or a sprocket The present invention can also be applied to a member (flange portion) such as a front portion 13 to which a crank pulley or the like is fitted, which needs to be provided with a highly accurate chamfered portion on the peripheral edge on the front side. .

  Of course, other specific forms can be adopted for matters other than the above as long as the technical significance of the present invention is not lost.

10 Coarse profile (crankshaft)
11 Pin portion 12 Journal portion 13 Front portion 14 Rear portion 15 O / S flange 16 F / W flange 17 Outer peripheral surface 18 Rear end surface 19 Chamfered portions 20, 21, 22 Tapered surfaces 23a, 23b, 23c Joints 26, 30 Grinding wheel 40 Lap device 41, 42 Clamp arm 43 Polishing film 44, 45 Recess 47 Shoe 48, 50 Taper-shaped pressing surface 49, 51 Movable shoe 100 Overall grinding wheel 101, 102, 103 Grinding surface

Claims (3)

A turning process for turning at least a predetermined flange portion , a pin portion, and a journal portion of the rough shape material of the crankshaft , and grinding with a grindstone on the flange portion , the pin portion, and the journal portion. and the grinding step, wherein the pin portion and the flange portion, and a finishing step of subjecting the pin section and the flange portion of the polishing film by causing relative sliding while pressing and polishing the journal portion to the journal portion A crankshaft manufacturing method including:
In the turning step, a chamfered portion having one or a plurality of tapered surfaces is formed on the periphery by turning the periphery of the flange portion.
In the grinding step, the chamfered portion of the flange portion is removed and grinding is performed on the outer peripheral surface and the end surface adjacent to the region, and
In the finishing step, by pressing the polishing film while sandwiching the flange portion with a clamp member having a cylindrical pressing surface corresponding to the outer peripheral surface and a tapered pressing surface corresponding to the tapered surface, A crankshaft manufacturing method in which an outer peripheral surface, the tapered surface, and a joint between them are polished. The chamfer has a plurality of tapered surfaces,
The clamp member includes a plurality of shoes having the cylindrical pressing surface, and a plurality of movable shoes each having the tapered pressing surface that is movable with respect to the shoe and corresponds to each of the tapered surfaces. ,
2. The method of manufacturing a crankshaft according to claim 1, wherein all the tapered surfaces can be polished by pressing the polishing film from a plurality of circumferential positions with the plurality of movable shoes. 3. Supplying the belt-like polishing film around the flange portion, and configured to be able to send the polishing film to one side in the longitudinal direction, and
The method of manufacturing a crankshaft according to claim 2, wherein the movable shoe corresponding to the tapered surface adjacent to the outer peripheral surface among the plurality of movable shoes is arranged on the most upstream side in the feeding direction of the polishing film.

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