JP2012097888A - Method of manufacturing crankshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a crankshaft in which a crank web and a counterweight are joined by welding, which can obtain a backup mechanism when a joint part is broken.SOLUTION: The crank web 2 and the counterweight 3 are joined by resistance welding (welding) in a welding process and are connected by plastic fastening in a bending process. Even if the joint part 21 by interference resistance welding is broken, a connection part 22 by the plastic fastening prevents the counterweight 3 from being separated from the crank web 2. Consequently, the connection part 22 by the plastic fastening can back up the joint part 21 by the interference resistance welding.

Description

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

  As a method for manufacturing a crankshaft for an automobile, a technique is known in which a crankshaft body and a counterweight are separately manufactured by cold forging, and the counterweight is joined to a crank web of the crankshaft body. This crankshaft manufacturing method can reduce the cost as compared with a method in which the crankshaft is integrally formed by hot forging. For example, Patent Document 1 discloses a technique in which a counterweight is fastened (joined) to a crank web using a bolt and a pair of positioning pins arranged on both sides of the bolt.

  By the way, due to the growing social interest in ecology, in the automobile industry, it has become a technical challenge to provide low fuel consumption vehicles at low prices. Therefore, further weight reduction and cost reduction are required for the crankshaft. Generally, a technique for reducing the thickness of the crank web (thickness stealing) is effective in reducing the weight of the crankshaft. However, if the weight of the crankshaft is reduced by this technique, the cross-sectional area of the crank web becomes smaller. The area of the joint between the crank web and the counterweight is reduced. For example, in the prior art described in Patent Document 1 described above, it is necessary to reduce the nominal diameter of the bolt to be used. Along with this, the joint strength between the crank web and the counterweight is lowered, so it is necessary to secure the joint strength by increasing the number of bolts to be used. However, when the number of bolts to be used is increased, the number of man-hours and the number of parts increase, leading to a decrease in productivity and an increase in manufacturing cost.

  Therefore, Patent Document 2 discloses a technique for joining a crank web and a counterweight by liquid phase diffusion bonding. However, liquid phase diffusion bonding needs to create an environment of a vacuum or an argon gas atmosphere at the time of joining. Therefore, the equipment cost and the running cost are increased. Furthermore, in the prior art described in Patent Document 2, a high bonding strength can be obtained by liquid phase diffusion bonding, but in order to further improve the reliability, a backup mechanism (mechanical backup) when the bonded portion is broken. Is required.

JP 2005-140337 A JP 2009-085316 A

  Accordingly, the present invention has been made in view of the above circumstances, and in a crankshaft in which a crank web and a counterweight are joined by resistance welding, a crankshaft manufacturing method that provides a backup mechanism in the case where the joint is broken It was made as an issue to provide.

  In order to solve the above-described problem, a crankshaft manufacturing method according to the present invention is a method of manufacturing a crankshaft by joining a crank web and a counterweight, and an axial direction of a journal is provided at an end of the counterweight. A projecting portion whose end is resistance welded to the end of the crank web, and a recess facing the end of the end of the crank web where the projecting portion is resistance welded. The crank in a state of being softened by Joule heat generated in the welding process by pressurizing the end of the end of the crank web by welding a welding process for joining the end of the counterweight and the protrusion of the counterweight by resistance welding The end portion of the web is bent in the axial direction of the journal and is plastically fastened to the concave portion of the counterweight. Characterized in that it comprises a lower step.

  In order to solve the above problems, the crankshaft manufacturing method of the present invention is a method of manufacturing a crankshaft by joining a crank web and a counterweight, and a journal is attached to an end of the counterweight. Providing a projecting portion projecting in the axial direction, bending the crank web end in the journal axial direction, and the crank web end and the counterweight end in the journal axial direction. The end of the crank web bent in the axial direction of the journal in the bending step and the protrusion of the counterweight are joined by resistance welding and softened by Joule heat generated by the resistance welding. The end of the crank web is made plastic to the protrusion of the counterweight. Characterized in that it comprises a welding step of sintering, the.

(Aspect of the Invention)
In the following, aspects of the invention that is recognized as being capable of being claimed in the present application (hereinafter referred to as claimable invention) will be exemplified, and each exemplified aspect will be described. Here, as in the claims, each aspect is divided into paragraphs, numbers are assigned to the respective paragraphs, and the descriptions of other paragraphs are cited as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combination of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiment, etc., and as long as the interpretation is followed, another aspect is added to the aspect of each section. Moreover, the aspect which deleted the component from the aspect of each term can also be one aspect of the claimable invention.
In the following items, each of the items (1) to (13) corresponds to each of claims 1 to 13 described in the claims.

(1) A method of manufacturing a crankshaft by joining a crank web and a counterweight, wherein a protrusion that protrudes in the axial direction of the journal and is welded to the end of the crank web at the end of the counterweight; A recess for facing the end of the end of the crank web to which the projection is welded, and a welding step for joining the end of the crank web and the projection of the counterweight by welding, and an end of the crank web Bending the end of the crank web softened by the welding heat generated in the welding process by pressurizing the tip to be bent in the axial direction of the journal and plastic fastening to the recess of the counterweight. A method for manufacturing a crankshaft.
According to the method for manufacturing a crankshaft described in this section, the crank web and the counterweight are joined by welding in the welding process and are joined by plastic fastening in the bending process. Even if it is destroyed, it is possible to prevent the counterweight from being separated from the crank web by the joint portion formed by plastic fastening. In other words, the joint by welding can be backed up by the joint by plastic fastening. Thereby, high performance and reliability required for the crankshaft can be ensured.
Also, in the bending process, the end of the crank web that has been softened by the welding heat generated in the welding process is bent, so the end of the crank web can be bent with a relatively small bending load, and processing with equipment with lower capacity is possible. Is possible.
Hereinafter, for convenience of explanation, the axial direction of the journal is defined as the Z direction, and the axial direction perpendicular to both the axial line of the crankpin supported by the target crank web and the journal is defined as the X direction (the Y direction is defined as the Y direction). , A direction perpendicular to both the Z direction and the X direction).
In the aspect of this section, for example, a concave portion having a substantially U-shaped cross section is formed at the end of the counterweight. Further, the protrusion portion of the counterweight is formed at the tip of the end portion of the counterweight so as to extend in the Z direction from the position of the bottom surface of the recess so as to share one wall surface of the pair of opposing wall surfaces of the recess. The Thus, the end portion of the counterweight is formed in a substantially L-shaped hook shape with a line of sight in the Y direction. In addition, the Z direction dimension of the edge part of a counterweight is set smaller than the Z direction dimension of the main-body part (connector) of a counterweight (for example, about 1/2).

(2) An end of the crank web is provided with a pressure-receiving surface that is inclined with respect to the plane perpendicular to the axis of the journal on the ridge opposite to the side where the protrusion of the counterweight is joined. The method for producing a crankshaft according to (1), characterized in that the pressure receiving surface of the crank web is pressed by the pressing surface of the tool to cause the end of the crank web to plastically flow toward the recess of the counterweight. .
According to the method for manufacturing a crankshaft described in this section, a pressure applied in a direction perpendicular to the pressure receiving surface is applied to the pressure receiving surface of the crank web by pressing the pressure receiving surface of the crank web with the pressing surface of the tool. As a result, the end of the crank web softened by the welding heat generated by welding is plastically flowed in the axial direction (Z direction) of the journal toward the counterweight recess, and plastically forms the counterweight recess. It is concluded.
In the aspect of this section, the direction of the pressing force of the tool may be either the Z direction or the X direction. However, since pressurization in the Z direction is difficult due to space constraints, it is desirable to set the direction in the X direction. . In this case, for example, the tool is formed in a substantially L-shaped cross section so as to avoid interference with the counterweight, and a pressure surface is formed at one end thereof.
The pressure-receiving surface of the crank web can be formed as a chamfered surface when the crank web is molded, and it is not particularly necessary to process and form the crank web after molding. In addition, the inclination angle of the pressure-receiving surface with respect to the journal axis perpendicular plane (XY plane) in the line of sight in the Y direction, that is, the inclination angle of the tool is 45 °, for example, so that the end of the crank web can be smoothly plastically flowed. In addition, it is desirable to set it to 45 ° or less.

(3) The end of the crank web is inclined with respect to the plane perpendicular to the axis of the journal, and the end of the crank web is formed into a tapered shape, and the counter web is formed with a tapered shape. In the weight recess, a pressure surface is provided to abut the end of the end of the crank web. In the bending process, the end of the end of the crank web is pressed in the abutting direction by the pressure surface of the counterweight. The method of manufacturing a crankshaft according to (1), wherein an end portion of the web is plastically flowed toward a concave portion of the counterweight.
According to the method for manufacturing a crankshaft described in this section, the end of the crank web is formed into a tapered shape, that is, the surface to which the protrusion of the counterweight is joined (the surface to which the journal is connected) The end of the crank web is tapered with respect to the XY plane at an inclination angle θ, and the end of the crank web is tapered with a line of sight in the Y direction. The end of the crank web softened by the welding heat generated in the welding process is plastically flowed toward the recess of the counterweight by being pressed against the pressurizing surface of the counterweight and joined to the end of the counterweight (plastic fastening) Can be made.
Compared with the embodiment of this section and the embodiment of (2), the embodiment of this section does not require a tool for bending the end of the crank web, that is, the workpiece (crank) between the welding process and the bending process. It is not necessary to move the shaft), and after welding (welding process), the end of the crank web is bent by pressing the end of the crank web with the pressure surface of the counterweight without moving the workpiece. Therefore, productivity can be improved.
In this aspect, the pressure surface of the counterweight moves the counterweight in the X direction with respect to the crank web in a state where the counterweight is positioned in the Z direction with respect to the crank web (positional relationship during welding). Thus, the end of the end of the crank web is abutted (abutted in a state of facing in the X direction). In addition, the pressure surface of the counterweight may be arranged parallel to the YZ plane, for example, at an appropriate inclination so that the end of the crank web bends more smoothly toward the recess of the counterweight during the bending process. It is also possible to provide a configuration.

(4) The method for manufacturing a crankshaft according to any one of (1) to (3), wherein the pressing force between the crank web and the counterweight is maintained for a predetermined time after the bending process is completed.
In the method of manufacturing a crankshaft described in the above items (1) to (3), if the applied pressure between the crank web and the counterweight is released immediately after the bending is completed, the crank web is moved by the spring back of the crank web. A gap is created between the end and the pressure surface of the counterweight, so that most of the heat at the end of the crank web is transferred to the journal. As a result, thermal distortion occurs in the journal, and the straightness of the journal is deteriorated. In the aspect of this section, it is possible to suppress the spring back of the crank web by holding the applied pressure between the crank web and the counterweight for a certain time after the bending is completed. As a result, the heat at the end of the crank web can be efficiently released to the counterweight, and deterioration of straightness due to thermal distortion of the journal is suppressed. Therefore, a highly accurate crankshaft can be obtained.
In the mode of this section, the straightness of the journal becomes higher as the holding time of the pressing force becomes longer, but the holding time of the pressing force is appropriately determined in consideration of required accuracy (journal straightness) and productivity. You only have to set it.

(5) In the welding process, the end of the crank web and the protrusion of the counterweight are joined by resistance welding, and the end of the crank web is softened by Joule heat generated by the resistance welding ( A method for producing a crankshaft according to any one of items 1) to (4).
According to the method for manufacturing a crankshaft described in this section, the number of welding processes and, hence, the manufacturing cost can be reduced compared to the case where the end of the crank web and the protrusion of the counterweight are joined by fusion welding. can do. In addition, the thermal distortion of the crankshaft (in particular, deterioration of the straightness of the journal) can be suppressed.

(6) In the welding process, the counterweight is pressurized in the direction perpendicular to the axis of the journal by the electrode, and the end of the crank web and the protrusion of the counterweight are subjected to interference resistance welding. (1) The manufacturing method of the crankshaft of the (5) term.
According to the method for manufacturing a crankshaft described in this section, the contamination layer on the surface is removed by the plastic deformation of the material by pressurization and the new surfaces are pressed together, so that the joining strength can be ensured. In this aspect, the counterweight is spaced from the crank web (in the X direction) at a position where the end of the counterweight (projection) overlaps the end of the crank web by, for example, 0.3 mm in the Z direction. In this state, by supplying a welding current to the electrode of the welding apparatus and moving the counterweight in the X direction by the electrode, the end of the crank web and the end of the counterweight (protrusion) are Interference resistance welding can be performed.
In the aspect of this section, the counterweight is pressurized in the X direction, that is, in a direction perpendicular to the axis of the journal. The pressure can be applied by the electrode, and the apparatus can be simplified and reduced in cost.

(7) The ends of the crank web are pressed in the butting direction by the pressure surface of the counter weight while welding the end of the crank web and the protrusion of the counter weight. (3) to (6) The method for producing a crankshaft in the item
According to the crankshaft manufacturing method described in this section, the welding process and the bending process can be performed in parallel, and the productivity can be further increased.
In this mode, the counter weight is moved in the X direction (abutting direction between the end of the end of the crank web and the end of the counter weight) by the electrode, and the end of the crank web and the end of the counter weight (protrusion) Can be easily implemented by interference resistance welding. In other words, by moving the counterweight in the X direction, the end of the crank web is pressurized by the pressure surface of the counterweight while joining the end of the crank web and the protrusion of the counterweight by interference resistance welding. Thus, by plastically flowing in the Z direction (journal axis direction), the end of the crank web softened by Joule heat of interference resistance welding can be plastically fastened to the recess of the counterweight.

(8) Item (3) to (7), wherein a notch is provided in the pressure surface of the counterweight, and the end portion of the crank web that is plastically flowed is coupled to the notch of the counterweight in the bending step. Method for manufacturing crankshafts.
According to the method of manufacturing a crankshaft described in this section, since the plastic flow material of the crank web is coupled to the notch of the counterweight, the counterweight can be more reliably detached from the crank web in the Y direction and the Z direction. Can be prevented.
In the aspect of this section, it is desirable to provide a plurality of notches. Further, the notch can be formed by, for example, protrusions provided at two corners of the pressure surface (the corner on the side opposite to the bottom surface side of the recess).

(9) A method of manufacturing a crankshaft by joining a crank web and a counterweight, wherein a protrusion projecting in the axial direction of the journal is formed at an end of the counterweight, and a recess facing the end of the crank web A bending process in which the end of the crank web is bent in the axial direction of the journal, and the end of the crank web and the end of the counterweight are pressurized in the axial direction of the journal, and the axial direction of the journal in the bending process A welding process in which the end of the crank web that has been bent to the counterweight and the protrusion of the counterweight are joined by welding, and the end of the crank web that has been softened by welding heat generated by welding is plastically fastened to the recess of the counterweight; The manufacturing method of the crankshaft characterized by including these.
According to the crankshaft described in this section, the crank web softened by the welding heat generated by welding while joining the end of the crank web bent in the axial direction of the journal and the projection of the counterweight by welding. Since the end of the plastic is fastened to the recess of the counterweight, even if the welded joint is destroyed, the counterweight is prevented from being separated from the crank web by the joint by plastic fastening. Can do. In other words, the joint by welding can be backed up by the joint by plastic fastening.
In the aspect of this section, for example, a concave portion having a substantially U-shaped cross section is formed at the end of the counterweight. Further, the protrusion portion of the counterweight is formed at the tip of the end portion of the counterweight so as to extend in the Z direction from the position of the bottom surface of the recess so as to share one wall surface of the pair of opposing wall surfaces of the recess. The Thus, the end portion of the counterweight is formed in a substantially L-shaped hook shape with a line of sight in the Y direction. In addition, the Z direction dimension of the edge part of a counterweight is set smaller than the Z direction dimension of the main-body part (connector) of a counterweight (for example, about 1/2).

(10) In the bending step, the end of the crank web is pressed in the axial direction of the journal by pressing the tip of the end of the crank web with the pressing surface of the tool inclined with respect to the plane perpendicular to the axis of the journal. The crankshaft manufacturing method according to item (9), which is characterized.
According to the method for manufacturing a crankshaft described in this section, the journal is connected in the Z direction (the axial direction of the journal) by pressing the end of the crank web with the pressing surface of the tool. It can be bent in the opposite direction to the opposite side to form a substantially L shape.
The tool used in the aspect of this section includes, for example, a first pressure surface inclined at a predetermined angle (for example, 45 °) with respect to an XY plane (a plane perpendicular to the axis of the journal) in a line of sight in the Y direction, and the first pressurizing surface. And a second machining surface disposed on the YZ plane continuously to the pressure surface. When using such a tool to bend the end of the crank web, press the end of the crank web in the X direction (the direction perpendicular to the axis of the journal) with the first pressure surface of the tool. The component force of the pressing force in the direction perpendicular to the first pressurizing surface acts on the end of the end of the crank web, and the end of the crank web bends in the Z direction along the first pressurizing surface. Next, the end of the crank web is pressed by the second pressurizing surface of the tool, whereby the end of the crank web can be bent in the Z direction to form a substantially L shape.

(11) The method for manufacturing a crankshaft according to (9) or (10), wherein the pressure applied between the crank web and the counterweight is maintained for a predetermined time after the welding process is completed.
In the crankshaft manufacturing method according to the above items (9) and (10), if the applied pressure between the crank web and the counterweight is released immediately after the welding is completed, the heat at the end of the crank web is increased. Part is transmitted to the journal. As a result, thermal distortion occurs in the journal, and the straightness of the journal is deteriorated. In the aspect of this section, the heat applied to the end of the crank web can be released to the counter weight by holding the applied pressure between the crank web and the counter weight for a certain time after the welding is completed. As a result, deterioration of straightness due to thermal distortion of the journal is suppressed, and it becomes possible to provide a highly accurate crankshaft.
In the mode of this section, the straightness of the journal becomes higher as the holding time of the pressing force becomes longer, but the holding time of the pressing force is appropriately determined in consideration of required accuracy (journal straightness) and productivity. You only have to set it.

(12) In the welding process, the end portion of the crank web is joined to the projection portion of the counterweight by resistance welding, and the end portion of the crank web is softened by Joule heat generated by the resistance welding ( 9. A method for producing a crankshaft according to items 9) to (11).
According to the method for manufacturing a crankshaft described in this section, the number of welding processes and, hence, the manufacturing cost can be reduced compared to the case where the end of the crank web and the protrusion of the counterweight are joined by fusion welding. can do. In addition, the thermal distortion of the crankshaft (in particular, deterioration of the straightness of the journal) can be suppressed.

(13) In the welding process, the counterweight is pressurized in the axial direction of the journal by the electrode, and the end portion of the crank web and the protrusion portion of the counterweight are subjected to interference resistance welding (9) A method for producing a crankshaft according to the item (12).
According to the method for manufacturing a crankshaft described in this section, the contamination layer on the surface is removed by the plastic deformation of the material by pressurization and the new surfaces are pressed together, so that the joining strength can be ensured. In the aspect of this section, the counterweight is spaced from the crank web by a distance of, for example, 0.3 mm in the X direction (for example, 0.3 mm) from the end of the counterweight (projection). In this state, by supplying a welding current to the electrode of the welding apparatus and moving the counterweight in the Z direction by the electrode, the end of the crank web and the end of the counterweight (protrusion) are Interference resistance welding can be performed.
In the aspect of this section, the end portion of the crank web formed in an approximately L shape and the end portion (protrusion portion) of the counterweight formed in an approximately L shape are engaged so as to overlap in the X direction. The centrifugal force of the counterweight at the time of rotating the shaft acts on the joint portion between the crank web and the counterweight in the compression direction, and the reliability of the joint portion between the crank web and the counterweight can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the crankshaft manufacturing method with which the back-up mechanism when a junction part is destroyed can be provided in the crankshaft which a crank web and a counterweight are joined by resistance welding.

It is explanatory drawing of 1st Embodiment, Comprising: It is a figure for demonstrating a welding process especially. It is explanatory drawing of 1st Embodiment, Comprising: It is a figure for demonstrating a bending process especially. It is explanatory drawing of 1st Embodiment, Comprising: It is a figure which shows the state by which the counterweight was attached to the crank web especially. It is an AA arrow line view in FIG. It is a figure which shows the taper shape formed in the edge part of the crank web of the crankshaft main body used by 2nd Embodiment. It is explanatory drawing of 2nd Embodiment, Comprising: It is a figure for demonstrating especially a welding process and a bending process. It is explanatory drawing of 2nd Embodiment, Comprising: It is a figure which shows the state by which the counterweight was attached to the crank web especially. It is explanatory drawing of 3rd Embodiment, Comprising: It is a figure which shows the state by which the applied pressure is hold | maintained especially after completion of joining. FIG. 9 is an enlarged view of a portion B in FIG. 8, and particularly shows a gap generated between the crank web and the counterweight due to the springback. It is an enlarged view of the B section in Drawing 8, and is a figure showing the state where spring back is suppressed especially. It is explanatory drawing of 3rd Embodiment, Comprising: It is a figure which shows the relationship between the holding time of pressurization force, and the straightness of a journal especially. It is explanatory drawing of 4th Embodiment, Comprising: It is the figure which looked at the crank web and the counterweight with the eyes | visual_axis from the Z direction especially. It is an enlarged view of the C section in FIG. It is explanatory drawing of 4th Embodiment, Comprising: It is the figure which looked at the crank web and the counterweight with the eyes | visual_axis from the Y direction especially. It is an enlarged view of the D section in FIG. It is explanatory drawing of 5th Embodiment, Comprising: It is a figure for demonstrating especially a bending process. It is explanatory drawing of 5th Embodiment, Comprising: It is a figure which shows the crank web especially given the bending process by a bending process. It is explanatory drawing of 5th Embodiment, Comprising: It is a figure for demonstrating a welding process especially.

A method for manufacturing a crankshaft according to the present invention will be described with reference to the accompanying drawings. Here, a method for manufacturing a crankshaft of an in-line four-cylinder engine for automobiles will be described. In the following description, directions are defined based on the coordinate system shown in FIGS.
A crankshaft manufactured using the manufacturing method of the present invention is a counterweight formed by cold forging on a crank web 2 (hereinafter simply referred to as crank web 2) of a crankshaft body 1 formed by cold forging. 3 can be obtained by bonding by the manufacturing method of the present invention. The counterweight 3 is roughly divided into a weight body 4 formed in an arc shape and a connection body 5 having one end connected to the crank web 2. The end portion of the counterweight 3 refers to one end portion of the connection body 5 provided with the protrusions 6 and the recesses 7, and the main body portion of the counterweight 3 refers to a portion excluding one end portion of the connection body 5. The counterweight 3 in FIGS. 1 to 3 has a simplified main body.

  As shown in FIGS. 1 to 3, a protrusion 6 and a recess 7 are provided at the end of the counterweight 3. The recess 7 has a pair of opposing wall surfaces 8 and 9 and a bottom surface 10 disposed parallel to the XY plane (or perpendicular to the axis Z of the journal 11), and the cross section in the ZX plane is substantially U-shaped. It is formed. The protrusion 6 is provided at the tip end of the counterweight 3 and has a height h in the Z direction (left and right direction in FIGS. 1 to 3) with respect to the bottom surface 10 of the recess 7. The protrusion 6 shares the recess 7 and the wall surface 8. Thereby, the edge part of the counterweight 3 is formed in a substantially L shape (reverse L shape) by the line of sight of the Y direction shown in FIGS. In a state where the end surface 6a of the protrusion 6 of the counterweight 3 and the wall surface 2a of the crank web 2 are in contact with each other (the wall surface opposite to the side to which the journal 11 is connected), the wall surface 2b of the crank web 2 ( The wall surface on the side to which the journal 11 is connected and one side surface (the left side surface in FIGS. 1 to 3) of the connection body 5 of the counterweight 3 are configured to be located on substantially the same plane.

(First embodiment)
A first embodiment of the present invention will be described. In 1st Embodiment, after joining the protrusion part 6 of the counterweight 3 by resistance welding (welding) to the edge part (lower end part in FIGS. 1-3) of the crank web 2 in a welding process, it is resistance in a bending process. The end portion of the crank web 2 softened by Joule heat (welding heat) generated by welding is bent by the tool 13 and is plastically fastened to the concave portion 7 of the counterweight 3. Here, at the edge of the crank web 2 on the side to which the journal 11 is connected, when the crankshaft body 1 is formed, a predetermined angle θ1 (for example, a plane perpendicular to the axis of the journal 11) is preliminarily formed with respect to the XY plane. A pressure-receiving surface 14 having a chamfered shape inclined at θ1 = 45 ° is formed.

  As shown in FIG. 2, the tool 13 has a substantially L-shaped cross section composed of a fixed portion 15 fixed to a ram or the like of a press device and a pressing portion 16 arranged in parallel to the XY plane. It has a mold. Further, the tool 13 extends slightly in the Z direction (right direction in FIG. 2) so that the end portion of the pressurizing portion 16 has a surface facing the fixed portion 15, and the end portion of the tool 13 has a crank web. A pressure surface 17 is formed in parallel with the two pressure receiving surfaces 14. Next, 1st Embodiment is demonstrated according to process.

(Welding process)
First, the crankshaft body 1 is fixed to a fixing jig, and the counterweight 3 is fixed to the movable electrode 18 of the interference resistance welding apparatus. In this state, the protrusion 6 of the counterweight 3 and the end of the crank web 2 overlap each other by, for example, 0.3 mm in the Z direction (left and right direction in FIG. 1), and a predetermined amount in the X direction (up and down direction in FIG. 1). Relative positioning is performed with a gap (a position where the counterweight 3 in FIG. 1 is indicated by a broken line). The fixed electrode 19 is in contact with, for example, the side of the crank web 2 to which the crank pin 20 is connected (see FIG. 1). From this state, a welding current is supplied between the electrodes 18 and 19 by the welding power source, and the counterweight is moved in the X direction (upward in FIG. 1) by driving the movable electrode 18. As a result, the interference portion between the end of the crank web 2 and the protrusion 6 of the counterweight 3 generates heat, and the end of the crank web 2 and the protrusion 6 of the counterweight 3 are joined by interference resistance welding. Part 21 is formed.

(Bending process)
Next, the workpiece with the counterweight 3 joined to the end of the crank web 2 is set on a fixing jig of a press device, and the pressure receiving surface of the crank web 2 to be machined as shown in FIG. 14 is brought into contact with the pressing surface 17 of the tool 13. From this state, the tool 13 is moved in the X direction (upward in FIG. 2) by driving the ram, so that the component force F1 of the applied pressure F in the X direction is applied to the pressure receiving surface 14 of the crank web. As a result, the end of the crank web 2 softened by Joule heat in the welding process plastically flows in the Z direction (the right direction in FIG. 2), and enters the recess 7 of the counterweight 3 as shown in FIG. The joint portion 22 is formed between the crank web 2 and the counterweight 3 by plastic fastening. 4 is an AA arrow view in FIG. 3 and shows a state in which the counterweight 3 is attached to the end of the crank web 2. FIG.

The first embodiment has the following effects.
According to the first embodiment, the crank web 2 and the counterweight 3 are joined by interference resistance welding in the welding process, and are joined by plastic fastening in the bending process. Even when the joint portion 21 is broken, it is possible to prevent the counterweight 3 from being separated from the crank web 2 by the joint portion 22 by plastic fastening. In other words, the joint portion 21 by interference resistance welding can be backed up by the joint portion 22 by plastic fastening. Thereby, high performance and reliability required for the crankshaft can be ensured.
Further, in the bending process, the end of the crank web 2 softened by the Joule heat generated in the welding process is bent, so that the end of the crank web 2 can be bent with a relatively small bending load (pressing force). It is possible to process with low equipment.

(Second Embodiment)
A second embodiment of the present invention will be described. In addition, about the structure which is the same as that of 1st Embodiment mentioned above, or equivalent, while giving the same name and code | symbol, the detailed description is abbreviate | omitted. In the second embodiment, the end of the crank web 2 is bent by the pressure surface 9 of the counterweight 3 (the wall surface 9 in the first embodiment) so that the welding process and the bending process can be performed in parallel. It is composed.
As shown in FIG. 5, the end portion of the crank web 2 has a wall surface 2 a (a wall surface opposite to the side to which the journal 11 is connected) having an inclination angle θ 2 with respect to the XY plane (a plane perpendicular to the axis of the journal 11). Is formed into a tapered shape by the wall surface 2a and the wall surface 2b (the wall surface to which the journal 11 is connected).

(Welding process)
First, the crankshaft body 1 is fixed to a fixing jig, and the counterweight 3 is fixed to the movable electrode 18 of the interference resistance welding apparatus. In this state, the protrusion 6 of the counterweight 3 and the end of the crank web 2 are relatively positioned so as to overlap each other by, for example, 0.3 mm in the Z direction and at a predetermined interval in the X direction (see FIG. 6). The position where the counterweight 3 is indicated by a broken line). From this state, a welding current is supplied between the electrodes 18 and 19 (see FIG. 1) by the welding power source, and the counterweight 3 is moved in the X direction (upward in FIG. 6) by driving the movable electrode 18. . As a result, the interference portion between the end of the crank web 2 and the protrusion 6 of the counterweight 3 generates heat, and the end of the crank web 2 and the protrusion 6 of the counterweight 3 are joined by interference resistance welding. Part 21 is formed. In FIG. 6, illustration of the fixed side electrode 19 is omitted.

(Bending process)
In the process of interference resistance welding, that is, when the counterweight 3 is moved by a predetermined distance in the X direction (upward direction in FIG. 6) by driving the movable side electrode 18, the tip end of the crank web 2 is counterweighted. 3 is pressed against the pressure surface 9. Then, the end portion of the crank web 2 is softened by Joule heat by interference resistance welding, and the wall surface 2a side is stealed and formed into a tapered shape (tapered shape). As shown in FIG. 6, the counterweight 3 is plastically deformed (bent) toward the concave portion 7 side (FIG. 6). Further, when the counterweight 3 is moved in the X direction (upward direction in FIG. 6), the end of the crank web 2 plastically flows toward the recess 7, and as a result, as shown in FIG. A joint portion 22 is formed between the crank web 2 and the counterweight 3 by plastic fastening.

The second embodiment has the following effects.
According to the second embodiment, in addition to the effects of the first embodiment described above, the bending load can be obtained by the force (pressing force) by which the movable electrode 18 presses the counterweight 3, so that the welding process and It is possible to perform the bending process in parallel. Furthermore, since it is not necessary to move the workpiece (crankshaft) between the welding process and the bending process, productivity can be greatly improved compared to the first embodiment.
Further, in the first embodiment described above, it was difficult to ensure the rigidity of the tool 13 due to space restrictions. However, in the second embodiment, the pressing surface 9 is provided on the counterweight 3 so that the tool 13 The problem about can be solved.
Furthermore, in the second embodiment, as compared with the first embodiment described above, it becomes possible to cause more material of the crank web 2 to flow plastically through the recesses 7 of the counterweight 3, and the crank web 2 and the counterweight 3 can be made to flow. It is possible to further improve the coupling force due to plastic fastening.

(Third embodiment)
A third embodiment of the present invention will be described. In addition, about the structure which is the same as that of the 1st and 2nd embodiment mentioned above, or equivalent, while giving the same name and code | symbol, the detailed description is abbreviate | omitted. In the third embodiment, the procedure (welding process and bending process) is basically the same as that of the second embodiment described above, but as shown in FIG. 8 after the end of bending of the crank web 2 is completed. The movable side electrode 18 is configured to hold the force (pressing force) for pressing the counterweight 3 for a certain period of time. In FIG. 8, illustration of the movable side electrode 18 and the fixed side electrode 19 is omitted.

The third embodiment has the following effects.
In the second embodiment described above, if the applied pressure between the crank web 2 and the counterweight 3 is released immediately after the bending is completed, the crank web 2 is spring-backed as shown in FIG. A gap is formed between the end of the web 2 and the pressure surface 9 of the counterweight 3. As a result, since most of the heat at the end of the crank web 2 is transferred to the journal 11, thermal distortion occurs in the journal 11, and the straightness of the journal 11 deteriorates.
In the third embodiment, in addition to the effects of the second embodiment described above, the pressure applied between the crank web 2 and the counterweight 3 is maintained for a certain period of time after the bending is completed, as shown in FIG. As described above, the spring back at the end of the crank web 2 can be suppressed to prevent a gap from being generated between the end of the crank web 2 and the recess 7 of the counterweight 3. As a result, the heat at the end of the crank web 2 can be efficiently released to the counterweight 3, and deterioration of straightness due to thermal distortion of the journal 11 is suppressed. As a result, a crankshaft with extremely high accuracy can be obtained.
As shown in FIG. 11, the straightness of the journal 11 increases as the holding time of the pressurizing force between the crank web 2 and the counterweight 3 becomes longer. However, since the man-hour is increased as the holding time of the pressing force becomes longer, it is desirable that the holding time of the pressing force is appropriately set in consideration of required accuracy (straightness of the journal 11) and productivity.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. In addition, about the structure which is the same as that of the 1st-3rd embodiment mentioned above, or equivalent, while giving the same name and code | symbol, the detailed description is abbreviate | omitted. In the fourth embodiment, the procedure (welding process and bending process) is basically the same as the second and third embodiments described above, but as shown in FIGS. 9 is different in that a counterweight 3 having a notch 23 formed in 9 is used.
The notches 23 are provided in two corners on one side (left side in FIG. 14) of the wall surface 9 of the counterweight 3, that is, a pair in the Y direction (left and right direction in FIG. 12). Each notch 23 is formed so as to protrude in the X direction (upward direction in FIGS. 12 and 14) like a fang, and is configured to be coupled to the plastic web 2 that is plastically flowed in the bending process. Yes.
Also in the fourth embodiment of the present invention, a joint 21 is formed between the end of the crank web 2 and the protrusion 6 of the counterweight 3 by interference resistance welding.

The fourth embodiment has the following effects.
In the fourth embodiment, in addition to the effects exhibited by the second and third embodiments described above, the end of the plastic web 2 that has been plastically flowed is coupled to each notch 23 of the counterweight 3, so that the counterweight 3 Can be reliably prevented from coming off from the crank web 2 in the Y direction (left-right direction in FIG. 12) and Z direction (left-right direction in FIG. 12).

(Fifth embodiment)
A fifth embodiment of the present invention will be described. In addition, about the structure which is the same as that of the 1st-4th embodiment mentioned above, or equivalent, while giving the same name and code | symbol, the detailed description is abbreviate | omitted. In the fifth embodiment, the end portion of the crank web 2 is bent by the tool 24, and then the end portion of the crank web 2 and the end portion of the counterweight 3 are joined.
As shown in FIG. 16, the tool 24 includes a first pressure surface 24a inclined at a predetermined angle θ3 (for example, θ3 = 45 °) with respect to the XY plane (a plane perpendicular to the axis of the journal 11), and the first pressure surface. And a second processed surface 24b disposed on the YZ plane continuously to 24a. Further, the tool 24 is attached to, for example, a mold holder of a press device and is driven in the X direction (vertical direction in FIG. 16).

(Bending process)
First, the crankshaft body 1 is fixed by a fixing jig (on the pressing device side). In this state, when the tool 24 is moved in the X direction (upward direction in FIG. 16), the first pressure surface 24 a of the tool 24 is abutted against the end of the end of the crank web 2. Then, the end of the crank web 2 is pressed in the X direction (the direction orthogonal to the axis Z of the journal 11) with the first pressing surface 24 a of the tool 24. As a result, the component force F2 of the applied pressure F (load) in the direction perpendicular to the first pressure surface 24a acts on the pressure receiving surface 14 of the crank web 2, and the end of the crank web 2 is located at the first pressure surface 24a. Along the Z direction (right side in FIG. 16). Subsequently, the end of the crank web 2 is pressed by the second pressurizing surface 24b of the tool 24 to bend the end of the crank web 2 along the second pressurizing surface 24b in the Z direction, as shown in FIG. Thus, it is formed in a substantially L shape.

(Welding process)
First, the crankshaft body 1 is fixed to a fixing jig (welding apparatus side), and the counterweight 3 is fixed to the movable electrode 18 of the interference resistance welding apparatus. In this state, the protrusion 6 of the counterweight 3 and the end of the crank web 2 (the tip portion bent in the Z direction) overlap each other by, for example, 0.3 mm in the X direction (vertical direction in FIG. 18) and in the Z direction. Relative positioning is performed with a predetermined interval (in the left-right direction in FIG. 18) (position where the counterweight 3 and the movable electrode 18 in FIG. 18 are indicated by broken lines). The fixed electrode 19 is in contact with the wall surface 2b on the side to which the journal 11 at the end of the crank web 2 is connected (see FIG. 18).

  From this state, a welding current is supplied between the electrodes 18 and 19 by the welding power source, and the counterweight is moved in the Z direction (left direction in FIG. 18) by driving the movable electrode 18. As a result, the interference portion between the end of the crank web 2 and the protrusion 6 of the counterweight 3 generates heat, and the end of the crank web 2 and the protrusion 6 of the counterweight 3 are joined by interference resistance welding. Part 21 is formed. Further, the counter weight 3 and the end of the crank web 2 softened by Joule heat generated by the interference resistance welding are pressurized by the Z-direction pressurizing force by the movable side electrode 18, whereby the crank web 2 The connecting portion 22 is formed in which the end portion of the counterweight is plastic-fastened to the concave portion 7 of the counterweight 3.

The fifth embodiment has the following effects.
According to the fifth embodiment, the crank web 2 and the counterweight 3 are joined by interference resistance welding in the welding process and joined by plastic fastening, so it is assumed that the joint portion 21 by interference resistance welding is used. Can be prevented from being separated from the crank web 2 by the coupling portion 22 by plastic fastening. In other words, the joint portion 21 by interference resistance welding can be backed up by the joint portion 22 by plastic fastening. Thereby, high performance and reliability required for the crankshaft can be ensured.

1 Crankshaft body, 2 Crank web, 3 Counterweight, 6 Projection, 7 Recess, 11 Journal, 21 Joint, 22 Joint, 23 Notch

Claims (13)

A method of manufacturing a crankshaft by joining a crank web and a counterweight,
Protruding portions that protrude in the axial direction of the journal and are welded to the end portions of the crank web at the end portions of the counterweight, and concave portions that face the tip ends of the crank web to which the protruding portions are welded are provided. Keep
A welding step of joining the end of the crank web and the protrusion of the counterweight by welding;
By pressurizing the tip of the end of the crank web, the end of the crank web that has been softened by the welding heat generated in the welding process is bent in the axial direction of the journal to be plastic in the recess of the counterweight. Bending process for fastening;
A method for manufacturing a crankshaft, comprising: On the edge of the end of the crank web opposite to the side on which the protrusion of the counterweight is joined, a pressure receiving surface inclined with respect to a plane perpendicular to the axis of the journal is provided,
2. The bending step is characterized in that an end portion of the crank web is plastically flowed toward a concave portion of the counterweight by pressing a pressure receiving surface of the crank web with a pressing surface of a tool. The manufacturing method of the crankshaft described in 2. The end of the crank web is inclined with respect to the plane perpendicular to the axis of the journal, and the end of the crank web is formed into a taper shape by inclining the surface to which the protrusion of the counterweight is joined. In the recess of the counterweight, a pressure surface on which the end of the end of the crank web is abutted is provided.
In the bending step, the end of the crank web is pressed in the abutting direction by the pressure surface of the counterweight to plastically flow the end of the crank web toward the recess of the counterweight. The method for manufacturing a crankshaft according to claim 1, wherein: The method of manufacturing a crankshaft according to any one of claims 1 to 3, wherein the pressure applied between the crank web and the counterweight is maintained for a certain time after the bending step is completed. In the welding step, the end of the crank web and the protrusion of the counterweight are joined by resistance welding, and the end of the crank web is softened by Joule heat generated by the resistance welding. The manufacturing method of the crankshaft in any one of Claims 1-4. In the welding step, the counterweight is pressurized by an electrode in a direction perpendicular to the axis of the journal, and the end of the crank web and the protrusion of the counterweight are interference resistance welded. The method for manufacturing a crankshaft according to claim 1, wherein: 7. The end of the crank web is pressed in the butting direction by the pressing surface of the counter weight while welding the end of the crank web and the protrusion of the counter weight. The manufacturing method of the crankshaft in any one of. A notch is provided on the pressure surface of the counterweight,
The method of manufacturing a crankshaft according to any one of claims 3 to 7, wherein, in the bending step, an end portion of the crank web that has been plastically flowed is coupled to a notch of the counterweight. A method of manufacturing a crankshaft by joining a crank web and a counterweight,
At the end of the counterweight, a protrusion protruding in the axial direction of the journal and a recess facing the end of the crank web are provided,
A bending step of bending an end of the crank web in the axial direction of the journal;
The end of the crank web and the end of the counterweight are pressed in the axial direction of the journal, and the end of the crank web and the protrusion of the counterweight are bent in the axial direction of the journal in the bending process. A welding step in which the end of the crank web softened by the welding heat generated by the welding is plastically fastened to the recess of the counterweight.
A method for manufacturing a crankshaft, comprising: In the bending step, the end of the crank web is pressed in the axial direction of the journal by pressing the tip of the end of the crank web with a pressing surface of a tool inclined with respect to a plane perpendicular to the axis of the journal. The method for manufacturing a crankshaft according to claim 9. 11. The method for manufacturing a crankshaft according to claim 9, wherein after the welding process is completed, a pressure force between the crank web and the counterweight is maintained for a predetermined time. In the welding step, the end of the crank web and the protrusion of the counterweight are joined by resistance welding, and the end of the crank web is softened by Joule heat generated by the resistance welding. The manufacturing method of the crankshaft in any one of Claims 9-11. In the welding step, the counterweight is pressurized in the axial direction of the journal by an electrode, and an end portion of the crank web and a protrusion of the counterweight are subjected to interference resistance welding. Item 15. A method for producing a crankshaft according to any one of Items 9 to 12.