JP5239465B2 - Method for manufacturing universal joint yoke - Google Patents

Description

  The present invention relates to an improvement in a manufacturing method of a yoke which is incorporated in, for example, a steering device of an automobile and constitutes a universal joint for transmitting the movement of a handle shaft to a steering gear. Specifically, regarding a method of manufacturing a yoke that is formed by bending a metal plate, when the metal plate is folded back approximately 180 degrees to make a flange portion, the metal plate is less likely to be damaged such as cracks. Therefore, it is intended to enable processing of a yoke having high strength and rigidity by using a metal plate having a large thickness.

  An automobile steering device is configured as shown in FIG. 11, for example. The movement of the steering wheel 1 is transmitted to the input shaft 6 of the steering gear unit 5 via a steering shaft 3 and an intermediate shaft 4 that are rotatably provided in the steering column 2. Then, the pair of left and right tie rods 7 and 7 are pushed and pulled based on the meshing of the rack and pinion built in the steering gear unit 5, and a predetermined amount corresponding to the steering amount of the steering wheel 1 is applied to the left and right steering wheels. Give the rudder angle. In the steering apparatus constructed and operated in this manner, the steering shaft 3 and the input shaft 6 of the steering gear unit 5 cannot normally be provided on the same straight line. For this reason, conventionally, the intermediate shaft 4 is provided, and both ends of the intermediate shaft 4 and the ends of the steering shaft 3 and the input shaft 6 are connected via universal joints 8 and 8 so that they are on the same straight line. The power transmission between the steering shaft 3 and the input shaft 6 which are not present in the engine can be performed.

  The universal joint used in such a case is called a so-called cardan joint, and is composed of a pair of yokes each formed in a bifurcated shape, and a cross shaft for linking these yokes in a displaceable manner. ing. In order to allow the steering device to be assembled, at least one of the yokes has a structure that can be attached to and detached from the end of the shaft with a bolt. By the way, as a yoke of such a universal joint, a metal plate (generally a steel plate) formed by bending a press working is conventionally known, for example, as described in Patent Documents 1 to 4. It is widely used because it is manufactured at low cost.

  12-13 has shown the universal joint 8a described in patent document 1 among these. The universal joint 8a includes first and second yokes 9 and 10 formed in a bifurcated shape by pressing a steel plate, and a cross for connecting the yokes 9 and 10 in a displaceable manner. It comprises a shaft 11. That is, of the four end portions provided on the cross shaft 11, the two end portions on the opposite side are respectively connected to the tip portions of the pair of arm portions 12 a and 12 b for each of the yokes 9 and 10. Inside the provided circular holes 16, 16, it is rotatably supported by a radial needle bearing or the like. The first yoke 9 of the yokes 9 and 10 is provided with a cylindrical portion 13 for externally fitting to the end portion of the shaft so as to be joined and fixed to the end portion of the shaft by welding or the like. . On the other hand, the second yoke 10 can be attached to and detached from the end of another shaft by a bolt (not shown).

  For this purpose, the second yoke 10 has a base cylindrical portion (the right half portion in FIG. 12) and a coupling cylinder portion 14 and a pair of flange portions 15a and 15b, which are in the shape of a left half in FIG. A pair of arm portions 12b and 12b are respectively formed on the half portion. A through hole 17 through which the bolt is inserted and a screw hole 18 through which the bolt is screwed are formed concentrically with each other at positions where the flanges 15a and 15b are aligned with each other. Further, the flange portions 15a and 15b have the steel plates folded back approximately 180 degrees and overlapped with each other so as to ensure the strength and rigidity by setting the thicknesses to two steel plates. In order to connect such a second yoke 10 and the end of the other shaft, the end of the shaft is inserted into the inner side of the connecting tube portion 14 and the through hole 17 is inserted. The bolt is screwed into the screw hole 18 and further tightened. In general, a female serration is formed on the inner peripheral surface of the coupling cylinder portion 14 and a male serration is formed on the end portion of the shaft, so that the relative rotation between the shaft and the second yoke 10 is reduced. To prevent.

  In order to manufacture such a second yoke 10, first, a steel plate as a material is punched out by pressing to produce an intermediate material 19 as shown in FIG. The intermediate material 19 includes a long rectangular base end side plate portion 20 and a pair of tongue pieces 21 protruding from two positions in the intermediate portion of the width direction one end edge (upper end edge in FIG. 14) of the base end side plate portion 20. , 21. Such an intermediate material 19 has a portion close to both ends in the length direction of the base end side plate portion 20 indicated by chain lines a and b in FIG. 14, and a thickness direction of the base end side plate portion 20 as shown in FIG. Are folded in the same direction and overlapped with the central portion of the base end side plate portion 20 to constitute a pair of flange portions 15a and 15b. Moreover, the intermediate part which exists in the part between these both flange parts 15a and 15b among the said base end side board parts 20 is made into the direction where the side which turned back the length direction both ends of this base end side board part 20 becomes a concave surface. As shown in FIGS. 12 to 13, the intermediate portion is formed as a non-cylindrical connecting tube portion 14. Further, the tongue pieces 21 and 21 are a pair of arms 12b and 12b protruding in the axial direction of the coupling cylinder 14 as shown in FIGS.

In this way, when the second yoke 10 is manufactured, in order to facilitate the folding at the chain lines a and b, Patent Document 2 discloses that the folding is performed at both ends in the width direction of the base end side plate portion. that Ru located provided a notch in a portion corresponding (by constricted this portion) is described. However, regarding the thickness of the steel plate in this portion, it is not intended to facilitate the folding particularly as it is as a raw material. For this reason, it is difficult to increase the thickness dimension of the steel sheet in consideration of preventing the occurrence of damage such as cracks in the folded portion, and by increasing the thickness dimension, the second It is difficult to improve the strength and rigidity of the yoke 10. The reason will be described below.

  As shown in FIG. 16, when the steel plate 22 is bent, a force in the compression direction is generated in the bent portion 23 on the inner side in the bending direction as indicated by arrows α and α, and on the outer side as indicated by arrows β and β. A force in the pulling direction is generated. Then, on the inside of the bent portion 23 based on the force in the compression direction, the surplus wall 24 gathers as shown by a diagonal lattice in FIG. 16, and this surplus wall 24 is resistant to further bending the steel plate 22. (This extra meat 24 stretches). Therefore, as the bending process of the steel plate 22 proceeds, the tensile force indicated by the arrows β and β increases. For this reason, the extension amount of the steel plate 22 exceeds the extension limit at the outer portion in the bending direction of the bent portion, and there is a high possibility that damage such as cracks occurs in the outer portion. As a result, a steel plate for producing the second yoke 10 cannot be used with a large thickness, and the degree of freedom in design for improving the strength and rigidity of the second yoke 10 is impaired.

Patent Document 3 describes a structure in which reinforcing ribs are formed on a part of the metal plate instead of folding the metal plate in order to ensure the strength and rigidity of the flange portion. In the case of such a conventional structure, cracking damage of the metal plate accompanying folding can be prevented, but the strength and rigidity obtained are inferior compared to the flange part of the folding structure. Further, Patent Document 4 discloses that a corner portion where stress is concentrated along with a bending process in which a part of a cross-shaped metal plate is folded by 90 degrees is crushed prior to the bending process. There is described an invention relating to a method for manufacturing a universal joint yoke, which reduces the wall thickness and prevents the corners from cracking. However, in the invention described in Patent Document 4 as described above, the portion where the thickness is reduced is not the folded portion, and the folded portion cannot be prevented from being damaged.
On the other hand, in the case of a so-called column type electric power steering apparatus in which an electric motor is incorporated in the steering column 2 as shown in FIG. 11, the torque transmitted by the universal joint is increased. Along with this, there is an increasing demand for improving the strength and rigidity by increasing the thickness of the yoke.

JP-A-55-142111 JP 2000-320564 A JP 2003-28187 A JP 2004-130322 A

  In view of the circumstances as described above, the present invention makes it difficult for cracks and other damage to occur when a metal plate is folded back to make a flange portion. The invention has been invented to realize a manufacturing method capable of improving the degree of freedom of design for obtaining a yoke having high strength and rigidity by enabling the use of a plate.

In the universal joint yoke manufacturing method according to the present invention, as in the conventional universal joint yoke manufacturing method described in Patent Document 1 described above, first, a steel plate as a material is stamped. By doing this, an intermediate material having a long rectangular base end side plate portion and a pair of tongue piece portions protruding from two intermediate portion positions of one end edge in the width direction of the base end side plate portion is made.
Next, by folding back the lengthwise ends of the base end side plate portion of the intermediate material in the same direction with respect to the thickness direction of the base end side plate portion and overlapping the portions near the center of the base end side plate portion. A pair of flange portions are formed.
Moreover, by curving the intermediate part which exists in the part between these both flange parts among this base end side board part in the direction where the side which turned back the length direction both ends of this base end side board part turns into a concave surface, The intermediate portion is a non-cylindrical connecting tube portion.
Furthermore, each said tongue piece part is made into a pair of coupling arms which protruded in the axial direction of this coupling cylinder part.

In particular, in the method for manufacturing a universal joint yoke according to the present invention, at the two positions near the both ends in the length direction of the base end side plate portion of the intermediate material, the folding directions for constituting both flange portions respectively. A pair of arcuate grooves having a cross-section are formed in the portion located on the inner side over the entire width of the proximal side plate portion by upsetting or cutting .
Then, the length direction near both ends portions of the proximal side plate portions, folded 180 degrees by the two groove portions, and overlay without central portion near the gap of the proximal side plate portion, and the flange portions.
Thereafter, a through hole for inserting the bolt and a screw hole for screwing the bolt are formed concentrically with each other at positions where both the flange portions are aligned with each other.
Of the processes for forming the both concave grooves at the two positions , the upsetting process is performed by crushing the two positions near the both ends in the length direction of the base end side plate portion of the intermediate material with a mold. Further, the cutting process is performed by scraping the two positions near the both ends in the length direction of the base end side plate portion of the intermediate material with a blade.

According to the method for manufacturing a universal joint yoke of the present invention configured as described above, when the metal plate is folded back to make the flange portion, it is difficult for the metal plate to be damaged such as a crack. That is, based on the presence of a pair of concave grooves formed over the entire width at two positions near the both ends in the length direction of the base end side plate portion of the intermediate material, when the base end side plate portion is folded back, The acting force in the compression direction can be kept small. For this reason, the surplus generated on the inner side in the folding direction is suppressed to a small extent, and the surplus generated also enters the both concave grooves and hardly resists further bending of the metal plate (does not stretch too much). ).
For this reason, even if it is considered to prevent the occurrence of cracks on the outer side in the folding direction, it becomes possible to adopt a metal plate having a larger thickness than in the past, and to obtain a yoke with high strength and rigidity. Improve design flexibility

[First example of embodiment]
1 to 9 show a first example of an embodiment of the present invention . In the case of carrying out the universal joint yoke manufacturing method of this example, first, a steel plate as a raw material is punched out by a press machine to produce a first intermediate material 25 as shown in FIG. The first intermediate material 25 includes a long rectangular base end side plate portion 20a and a pair of tongue pieces protruding from two positions in the intermediate portion of the width direction one end edge (upper end edge in FIG. 1) of the base end side plate portion 20a. Parts 21a and 21a. In the case of this example, V-shaped notches 26 and 26 are formed at both ends of the base end side plate portion 20a in the width direction at both ends of the intermediate end portion of the base end side plate portion 20a. The part is constricted (the width dimension of this part is reduced).

  The first intermediate material 25 is subjected to a surface pressing process which is a feature of this example, and on one side of the proximal end side plate portion 20a near the both ends of the intermediate portion, respectively, between the notches 26 and 26, respectively. Concave grooves 27 and 27 are formed to form a second intermediate material 28 as shown in FIG. In the surface pressing process for forming the concave grooves 27, 27, a pair of protrusions provided on the lower surface of the pressing die is formed in a state where the base side plate portion 20a is placed on the upper surface of the flat receiving die. , By pressing strongly between the notches 26, 26. As a result of this pressing, the shape of the both ridges is transferred to one surface of the proximal end side plate portion 20a near both ends of the intermediate portion, and a concave groove 27 having a circular arc cross section as shown in FIG. , 27 are formed in the part between the notches 26, 26 facing each other over the entire width of the part between them. Further, in the case of this example, chamfered portions are formed on both side edge portions of the both tongue piece portions 21a and 21a and between the both tongue piece portions 21a and 21a at the intermediate side edge of the base end side plate portion 20a. The inclined surfaces 29a and 29b are formed. These inclined surfaces 29a and 29b are provided in order to ensure the required joint angle while preventing interference with the counterpart yoke when a universal joint is formed.

  The second intermediate material 28 as described above is a portion close to both ends in the length direction of the base end side plate portion 20a in which the both concave grooves 27, 27 are formed, and the double concave grooves shown in FIG. The central portions of 27 and 27 are folded in the same direction with respect to the thickness direction of the base end side plate portion 20a to form a third intermediate material 30 as shown in FIG. In the case of this example, based on the presence of the both concave grooves 27, 27, the operation of folding the portions near the both ends in the length direction of the base end side plate portion 20a as described above is easily performed (with a light force). The pulling force acting on the outside in the folding direction can be suppressed. This point will be described with reference to FIG.

  As shown in FIG. 4, when folding the portions near the both ends in the length direction of the base end side plate portion 20a, a force in the compression direction is generated as indicated by arrows α and α inside the folding portion 23a in the folding direction. On the outside, a pulling force is generated as indicated by arrows β and β. Then, on the basis of the force in the compression direction, the surplus wall 24a is gathered inside the bent portion 23a as shown by an oblique lattice in FIG. This is the same as in the case of the conventional method shown in FIG. However, in the case of this example, since the both concave grooves 27 and 27 are present in the portion where the surplus material 24a is gathered inside the bent portion 23a, a crack or the like is formed in the outer portion in the bent direction of the bent portion 23a. Damage is unlikely to occur.

  That is, when the bent portion 23a is formed by folding the portions near the both ends in the length direction of the base end side plate portion 20a, it is based on the compressive stress in the directions of the arrows α and α generated inside the bent portion 23a. The surplus wall 24a is formed so as to fill the concave groove 27. The inner portion of the bent portion 23a in the bending direction has low rigidity against the compressive stress in the directions of the arrows α and α based on the presence of the concave groove 27. Further, if the size (depth and width) of the concave groove 27 is appropriately regulated (sufficiently secured), in the process of forming the bent portion 23a, the bent portion 23a is further connected to the proximal side plate portion 20a. The concave groove 27 is not completely filled up with the surplus wall 24a in the process of folding until it is overlapped with the intermediate portion. Therefore, the extent to which the inner side portion of the bent portion 23a including the surplus portion 24a folds the portion near the both ends in the length direction of the base end side plate portion 20a and further pushes it against the force of turning back can be kept low. For this reason, the amount of extension of the steel plates constituting the second intermediate material 28 to the third intermediate material 30 at the outer portion in the bending direction of the bent portion 23a can be kept within the extension limit. As a result, it is possible to effectively prevent the occurrence of damage such as cracks in the outer portion.

  As described above, the third intermediate material 30 in which the pair of bent portions 23a and 23a is formed is then further increased in the amount of bending of both the bent portions 23a and 23a, as shown in FIG. The four intermediate materials 31 are used. Next, the pair of bent portions 23a and 23a are further bent from the state of the fourth intermediate material 31 (a total of 180 degrees from the beginning of processing), and both the bent portions 23a and 23a are connected to the proximal end side plate portion 20a. The fifth intermediate material 32 as shown in FIG. Even in such a bending process, based on the presence of the both concave grooves 27, 27, the amount of extension of the steel sheet in the outer part in the bending direction is kept within the limit and damage such as cracks occurs in the outer part. Things can be effectively prevented. Further, the bent portions 23a, 23a can be overlapped with the intermediate portion of the base end side plate portion 20a without a gap. That is, the gaps 33 and 33 do not occur between the stacked steel plates as in the flange portion produced by the conventional method shown in FIGS.

The fifth intermediate material 32 as described above is subjected to press working to form a pair of arm portions 12 and 12 by bending the pair of tongue pieces 21a and 21a in the next step, as shown in FIG. The sixth intermediate material 34 is used. Note that FIG. 6A and FIG. 7A are reversed.
Such a sixth intermediate material 34 has a seventh intermediate material as shown in FIG. 8 by pre-forming by bending the intermediate portion of the base end side plate portion 20a with the surface where the two bent portions 23a and 23a are overlapped as a concave surface. Through step 35, the eighth intermediate material 36 shown in FIG.

The eighth intermediate material 36 includes a base cylindrical portion {lower half of FIGS. 9A and 9C} having a cylindrical coupling cylinder portion 14a and a pair of flange portions 15c and 15d, and a leading half { A pair of arms 12 and 12 are provided in the upper half of FIGS. 9A and 9C, respectively.
In such an eighth intermediate material 36, concentric circular holes 16 (see FIG. 12) are formed at the tip portions of the both arm portions 12, 12 by a subsequent punching process or drilling process. Further, by drilling and tapping, a through hole 17 for inserting a bolt and a screw hole 18 (see FIG. 13) for screwing the bolt into positions where the flanges 15c and 15d are aligned with each other. Are formed concentrically with each other. Further, finish processing such as deburring of each part is performed to complete a universal joint yoke.

  In the case of the method for manufacturing a universal joint yoke according to this example, in the process of processing the second intermediate material 28 into the fifth intermediate material 32, the steel plate is lightly applied based on the presence of the both concave grooves 27, 27. Can be folded and folded further. For this reason, even if this steel plate is bent at a normal temperature by cold working, both the flange portions 15c and 15d can be formed easily and stably. In addition, it is possible to use thicker steel plates than conventional ones (for example, 6.5 mm from the past → 8.0 mm of the present invention), and a universal joint having sufficient strength and rigidity, regardless of being costly forged. Yoke can be obtained. In addition, since the process of heating or cooling the steel sheet is not required for improving workability, a highly accurate universal joint yoke can be manufactured at low cost and with a short lead time.

Further, the both concave grooves 27, 27 are formed, and the surplus wall 24a (see FIG. 4) generated by the bending process is accommodated in the both concave grooves 27, 27. It can be reduced. Since this surplus thickness 24a is not useful in terms of the function of the universal joint yoke, the necessary functions can be impaired by forming both the concave grooves 27 and 27 and further reducing the amount of surplus thickness 24a. The weight of the universal joint yoke obtained can be reduced.
Further, since both the bent portions 23a, 23a constituting the flange portions 15c, 15d and the proximal end side plate portion 20a are overlapped without gaps, when the through hole 17 and the screw hole 18 are processed, The accompanying shavings and burrs do not enter between the bent portions 23a, 23a and the proximal side plate portion 20a. Therefore, the through hole 17 and the screw hole 18 can be stably processed, and the shavings and burrs can be easily removed, and the processing cost can be reduced from this surface.

[Second Example of Embodiment]
In the case of the first example described above, the pair of concave grooves 27 and 27 are formed by strongly pressing a pair of protrusions provided on the lower surface of the pressing die against the substrate side plate portion 20a. From the aspect of shortening the machining time, preventing the occurrence of shavings, ensuring the yield of the material, and reducing the machining cost of the above-mentioned double-grooves 27, 27, these double-concave grooves can be formed by the above-described upsetting process. Preferably, 27 and 27 are formed. However, if these concave grooves 27 and 27 are formed by upsetting, the portion corresponding to the bottom of the concave grooves 27 and 27 where the substrate side plate portion 20a should be bent is work-hardened and required for bending. This is disadvantageous in terms of reducing power. And depending on the thickness, type, etc. of the steel plate, damage such as cracks may occur in the bent portion.
Therefore, when it is difficult to adopt upsetting due to the thickness of the steel sheet, the two protrusions 27, 27 are cut off at two positions near the both ends in the length direction of the base end side plate portion of the intermediate material by a blade. Formed by cutting. As the blade used in this case, for example, an end mill can be adopted.

[ Reference Example for the Present Invention ]
Further, even when forming a concave groove on one side of the base end side plate portion 20a by pressing, as shown in FIG. 10, by bending the steel plate itself constituting the base end side plate portion 20a, Concave grooves 27a and 27a can be formed at portions near both ends of one side of the base end side plate portion 20a. Such concave grooves 27a and 27a can suppress a molding load lower than the upsetting process of the first example of the embodiment described above. However, the shape of the flange portion to be obtained is restricted because the portion on the opposite side of the other surface of the base end side plate portion 20a bulges out from the concave grooves 27a and 27a.

The front view (A) and end view (B) of the 1st intermediate material made at the 1st process of the 1st example of an embodiment of the invention. The front view (A) and end view (B) of the 2nd intermediate material made in the said 2nd process. The front view (A) and end view (B) of the 3rd intermediate material made in the 3rd process. Sectional drawing for demonstrating the state of the force added to each direction at the bending raising part at the time of this 3rd process. The front view (A) and end elevation (B) of the 4th intermediate material made at the 4th process of the manufacturing method of the present invention. The front view (A) and end view (B) of the 5th intermediate material made in the 5th process. The front view (A), end view (B), and side view (C) of the sixth intermediate material produced in the sixth step. The end view of the 7th intermediate material made in the 7th process. The front view (A), end view (B), and side view (C) of the eighth intermediate material made in the eighth step. The front view (A) and end view (B) of the 1st intermediate material made at the 1st process of the 3rd example of an embodiment of the invention. The partial cutting side view which shows an example of the steering device incorporating a universal joint. The perspective view which shows one example of the universal joint known conventionally. XX sectional drawing of FIG. The front view of the 1st intermediate material made in the 1st process of the conventional manufacturing method. Sectional drawing of the intermediate material produced in the said 2nd process. Sectional drawing for demonstrating the state of the force added to each direction at the bending raising part at the time of this 2nd process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering column 3 Steering shaft 4 Intermediate shaft 5 Steering gear unit 6 Input shaft 7 Tie rod 8, 8a Universal joint 9 First yoke 10 Second yoke 11 Cross shaft 12, 12a, 12b Arm part 13 Cylindrical part 14 , 14a Connecting cylinder part 15a, 15b, 15c, 15d Flange part 16 Circular hole 17 Through hole 18 Screw hole 19 Intermediate material 20, 20a Base end side plate part 21, 21a Tongue piece part 22 Steel plate 23, 23a Bending part 24, 24a Extra Meat 25 First intermediate material 26 Notch 27, 27a Groove 28 Second intermediate material 29a, 29b Inclined surface 30 Third intermediate material 31 Fourth intermediate material 32 Fifth intermediate material 33 Gap 34 Sixth intermediate material 35 Seventh intermediate Material 36 Eighth Intermediate Material

Claims (1)

By punching a steel plate as a raw material, an intermediate portion having a long rectangular base end side plate portion and a pair of tongue pieces projecting from two intermediate portion positions of one end edge in the width direction of the base end side plate portion Make a material, and fold the length of the intermediate material near the both ends of the base side plate in the same direction with respect to the thickness direction of the base side plate and overlap the portion near the center of the base side plate As a result, a pair of flange portions are formed, and an intermediate portion existing between the flange portions of the proximal end side plate portions is folded back at both longitudinal ends of the proximal end side plate portions. By curving in a direction in which the side becomes a concave surface, the intermediate portion is made into a non-cylindrical coupling tube portion, and the both tongue pieces are each made a pair of coupling arms protruding in the axial direction of the coupling tube portion. In the method of manufacturing a universal joint yoke,
A pair of arc-shaped concave grooves having a pair of cross-sections are formed at portions located on the inner side with respect to the folding direction for constituting both flange portions at two positions near both ends in the length direction of the base side plate portion of the intermediate material. by machining or cutting upsetting, after forming over the entire width of the base end side plate portions, the longitudinal ends near portion of the proximal side plate portions, folded 180 degrees by the two grooves moiety, the group and overlay without gaps and inboard portion of the end plate portion, and the flange portions,
Thereafter, a through hole for inserting a bolt and a screw hole for screwing the bolt are formed concentrically with each other at positions where both the flange portions are aligned with each other. A method of manufacturing a joint yoke.

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