JP5029723B2 - Yoke for cross shaft type universal joint and method for manufacturing the same - Google Patents

Description

  The present invention relates to a yoke that constitutes a cross-shaft universal joint (cardan joint) for connecting the rotating shafts that constitute a steering apparatus for an automobile so that torque can be transmitted, and an improvement of the manufacturing method thereof. Specifically, the metal plate is subjected to press working such as punching and bending, and a yoke structure having a pair of flange portions having a thickness dimension corresponding to two metal plates and a manufacturing method thereof are devised. By doing so, it is possible to achieve both the securing of the relative displacement amount in the axial direction of the yoke and the rotating shaft and the weight reduction, and the structure capable of sufficiently ensuring the accuracy of the coupling portion between the yoke and the rotating shaft, and This manufacturing method is to be realized.

  The vehicle steering apparatus is configured as shown in FIG. 4, and transmits the rotation of the steering wheel 1 to the input shaft 3 of the steering gear unit 2, and a pair of left and right tie rods 4 according to the rotation of the input shaft 3, 4 is pushed and pulled to give a steering angle to the front wheels. The steering wheel 1 is supported and fixed to the rear end portion of the steering shaft 5, and the steering shaft 5 is rotatably supported by the steering column 6 with the cylindrical steering column 6 inserted in the axial direction. Has been. Further, the front end portion of the steering shaft 5 is connected to the rear end portion of the intermediate shaft 8 via a universal joint 7, and the front end portion of the intermediate shaft 8 is connected to the input shaft 3 via another universal joint 9. Connected to. The illustrated example incorporates an electric power steering device that reduces the force required to operate the steering wheel 1 using the electric motor 10 as an auxiliary power source. Therefore, the front end portion of the steering shaft 5 is connected to the input side of the electric power steering device, and the output shaft of the electric power steering device and the rear end portion of the intermediate shaft 8 are connected by the universal joint 7. Torque transmission is connected freely.

  The universal joint 7 connected to the steering shaft 5, the intermediate shaft 8, and the input shaft 3, which are rotating shafts that are incorporated in the above-described steering apparatus for an automobile and do not exist on the same straight line. Reference numeral 9 denotes a cross shaft type universal joint that incorporates a yoke that is the object of the manufacturing method of the present invention. Such universal joints have been conventionally known in various structures as described in Patent Documents 1 to 5, for example. FIG. 5 shows an example of the structure described in Patent Document 1 among them. The universal joint 11 shown in FIG. 5 is formed by connecting a pair of yokes 12a and 12b via a single cross shaft 13 so that torque can be transmitted. In the case of the illustrated example, both of the yokes 12a and 12b are made by stamping and bending a metal plate having sufficient strength and rigidity, such as a steel plate, respectively. 14a and 14b, and a pair of connecting arm portions 15a and 15b for each of the yokes 12a and 12b.

  Of these, the base portions 14a and 14b include first flange portions 16a and 16b and second flange portions 17a and 17b, respectively. The first flange portions 16a and 16b and the second flange portions 17a and 17b are provided with a discontinuous portion 18a and 18b provided at one place in the circumferential direction of the base portions 14a and 14b, respectively. . A pair of mounting holes for each of the two base portions 14a and 14b is provided at a position where the first and second flange portions 16a, 16b, 17a and 17b are paired with each other for the two base portions 14a and 14b. Each of these base portions 14a and 14b is formed in a direction that is a torsional positional relationship with respect to the axial direction.

  In addition, a pair of coupling arm portions 15a and 15b for each of the yokes 12a and 12b is rotated to be coupled and fixed to the base portions 14a and 14b at the front end edges of the base portions 14a and 14b of the yokes 12a and 12b, respectively. The shafts 19a and 19b extend in the axial direction from two positions on the diametrically opposite side. Then, circular holes 20a and 20b are respectively formed at the distal ends of the coupling arm portions 15a and 15b, and are formed concentrically with each other between the pair of coupling arm portions 15a and 15b for each of the yokes 12a and 12b. ing. The four shaft portions provided on the cross shaft 13 inside the circular holes 20a and 20b are rotatably supported by radial bearings 21a and 21b, each of which is a shell type needle bearing. With such a structure, the yokes 12a and 12b are combined so that torque can be transmitted even when the central axes of the base portions 14a and 14b are inclined.

  When assembling a steering apparatus for an automobile as described above, the universal joint 11 as described above does not exist on the same straight line (the steering shaft 5, the intermediate shaft 8, and the input shaft 3 are mutually connected. A pair of rotating shafts 19a and 19b (which are any two adjacently arranged and the respective central axes are inclined with respect to each other) are coupled so as to be able to transmit torque. For this purpose, the bolts 22a are inserted into the ends 14a and 14b of the yokes 12a and 12b and the mounting holes formed in the bases 14a and 14b are inserted into the ends of the rotary shafts 19a and 19b. 22b and nuts 23a and 23b are screwed together and further tightened. And the outer peripheral surface of the edge part of both the rotating shafts 19a and 19b is strongly suppressed by the inner surface of both the base parts 14a and 14b. In this state, the two rotary shafts 19a and 19b are coupled via the universal joint 11 so as to be able to transmit torque.

  Of the pair of yokes 12a and 12b constituting the universal joint 11 shown in FIG. 5, one yoke 12b (the left side in FIG. 5) has a female serration formed on the inner peripheral surface of the base portion 14b and the above-described female serration. By engaging the male serration formed on the outer peripheral surface of the end portion of the rotating shaft 19b, a large torque can be transmitted between the base portion 14b and the rotating shaft 19b. Accordingly, when the base portion 14b and the rotating shaft 19b are coupled, the base portion 14b and the rotating shaft 19b are relatively displaced in the axial direction. On the other hand, the base portion 14a of the other yoke 12a (on the right side in FIG. 5) is a so-called horizontal insertion type yoke having a U-shaped cross section or a U-shaped cross section that is open on the side. This base portion 12a can be inserted from the side. In the present specification, for convenience of explanation, as described above, while the base portion and the rotating shaft are relatively displaced in the axial direction, the female serrations formed on the inner peripheral surface of these base portions and the outer peripheral surface of the end portion of the rotating shaft. A yoke having a structure for engaging with the formed male serration is a vertical insertion type yoke.

  Also, as shown in FIGS. 6 to 7, one of the pair of mounting holes formed in alignment with the first and second flange portions 16c and 17c provided on the yoke 12c is bolt 22c. A structure in which the nut is omitted by using the other mounting hole as a screw hole 25 for screwing the bolt 22c, and a structure in which a nut is omitted, has been conventionally used, for example, as described in Patent Documents 3 and 5. Widely known. The yoke 12c is a so-called press yoke in which a metal plate is sequentially punched and bent by a press. A female serration is formed on the inner peripheral surface of the base portion 14c except for the discontinuous portion 18c and the vicinity thereof. ing. Further, the first and second flange portions 16c and 17c are made to have a thickness dimension corresponding to two metal plates by folding the metal plate. Such a structure and manufacturing method of a press yoke have been conventionally known, for example, as described in Patent Document 5. The present invention relates to an improvement of such a press yoke and its manufacturing method, and therefore a manufacturing method obtained by slightly improving the manufacturing method described in Patent Document 5 will be described with reference to FIG. To do.

In this manufacturing method, first, a metal plate having sufficient rigidity, such as a steel plate, is punched out by press working, so that a substrate portion 26 and a pair of tongue-like portions 27 and 27 as shown in FIG. A flat base plate 28 having the above is obtained.
If the base plate 28 as described above is obtained by punching, then, in the substrate portion 26 constituting the base plate 28, both end portions projecting from the both tongue portions 27, 27 are respectively connected to the respective base portions 28. At the middle portion in the length direction, the pair of overlapping portions 29 and 29 are formed by folding back 180 degrees densely (with as much curvature as possible) in the same direction with respect to the thickness direction of the substrate portion 26. Thus, the first intermediate material 30 as shown in FIG.

  Next, the first intermediate material 30 is pressed between a pair of pressing dies to be plastically deformed, whereby a second intermediate material 31 as shown in FIG. 8C is obtained. The second intermediate material 31 is to be a pair of connecting arm portions 15b and 15b (see FIG. 6), and the tongue portions 27 and 27 are curved in a partial cylindrical shape. The proximal end portion of the tongue portion 27 is bent in a substantially crank shape, and the intermediate portion or the distal end portion portion of the tongue portions 27 and 27 is offset with respect to the substrate portion 26.

Next, the second intermediate material 31 as described above is bent slightly at the central portion of the substrate portion 26 (more than 90 degrees and less than 180 degrees, for example, about 130 to 150 degrees) as shown in FIG. The third intermediate material 32 as shown is assumed.
Next, the substrate portion 26 of the third intermediate material 32 is further curved (from a flat plate state to 180 degrees) to form a fourth intermediate material 33 as shown in FIG. In this state, a base portion 14c and a pair of arm portions 15b and 15b provided in the completed yoke 12c (see FIG. 7) are formed. Therefore, finally, through holes 24 and screw holes 25 are formed in the first and second flange portions 16c and 17c constituting the base portion 14c, and circular holes 20b and 21b are formed in the both arm portions 15b and 15b (FIG. 6 to FIG. 6). 7) are respectively formed to complete the yoke 12c as shown in FIGS.

  For example, in the case of the vertically inserted yoke 12c manufactured by the manufacturing method as described above, when the base 14c of the yoke 12c and the end of the rotary shaft 19b are attached and detached, the base 14c and the rotary shaft 19b are It is necessary to make a relative displacement in the axial direction. Like the universal joint 11 shown in FIG. 5 described above, in the case of a structure in which a vertically inserted yoke 12b and a horizontally inserted yoke 12a are combined, the base portion 14b of the vertically inserted yoke 12b and the rotary shaft 19b are arranged. If the end portion is first coupled and fixed, and then the transversely inserted yoke 12a and the end portion of the rotating shaft 19a are coupled and fixed, the two rotating shafts 19a and 19b can be coupled to each other with inclination. When separating the rotary shafts 19a and 19b from each other, conversely, if the coupling between the lateral insertion type yoke 12a and the end of the rotary shaft 19a is removed first, the vertical insertion type yoke 12b is The coupling with the end of the rotating shaft 19b can be removed. However, the attachment / detachment work between the lateral insertion type yoke 12a and the end of the rotary shaft 19a requires a certain amount of space on the side. For this reason, depending on the structure of the vehicle to be mounted, it may be required that the pair of yokes constituting the universal joint be vertically inserted.

  However, when each of the pair of yokes is vertically inserted, with respect to any one of the yokes, the inner peripheral surface of the base portion and the outer peripheral surface of the end portion of the rotating shaft remain serrated and engaged. It is necessary to ensure a sufficient amount (possible stroke amount) that can relatively displace the end of the rotating shaft in the axial direction. The reason for this is that after the end of one rotary shaft is serrated to the base of one of the yokes, the base of the other yoke is serrated to the end of the other rotary shaft. This is to prevent interference between the end surface of the one rotating shaft and the cross shaft when increasing the amount of insertion of the end of the one rotating shaft into the base of the one yoke.

  For example, FIG. 9 shows a press yoke formed by pressing a metal plate as the yoke 12d configured to satisfy the above-described requirements (so that the possible stroke amount can be secured as the one yoke). Yes. The yoke 12d has a sufficiently large axial length of the base portion 14d including the first and second flange portions 16d and 17d and the discontinuous portion 18d. However, the through hole 24 and the screw hole 25 through which the bolt 22c {see FIG. 7 (B)} is inserted are the base ends (the ends opposite to the pair of coupling arms 15b and 15b) of the flange portions 16d and 17d. , The lower end of FIG. This is because, in a state where the base portion 14d and the end portion of the rotating shaft 19b (see FIG. 7) are coupled and fixed, the end portion of the rotating shaft 19b exists only in the portion near the base end of the base portion 14d. This is because it does not exist near the tip of the base portion 14d.

  If the yoke 12d as shown in FIG. 9 is used, even if each of the pair of yokes is a universal joint, the pair of adjacent rotating shafts can be coupled to each other. In this connecting operation, first, the end of one rotary shaft is serrated to the base 14d of the yoke 12d having the large axial length of the base 14d, and the end of the rotary shaft is as far back as possible from the base 14d. (Until the end surface of the rotating shaft hits the cross shaft or just before it). In this state, the base end opening of the base of the other yoke and the front end surface of the other rotating shaft are aligned (opposed with their center axes coincident with each other). Next, the base portion of the other rotating shaft is serrated to the end portion of the other rotating shaft while moving the end portion of the one rotating shaft from the base portion 14d in the direction of pulling out. Even when the base of the other yoke and the end of the other rotating shaft are sufficiently serrated (for the required axial length), the base 14d of the yoke 12d and the one rotation The end of the shaft remains in a sufficiently serrated engagement. Therefore, the diameters of the base portions of both yokes are reduced by tightening bolts, and the base portions of both yokes and the end portions of the rotating shafts are coupled and fixed.

  The yoke 12d shown in FIG. 9 as described above has no problem in terms of enabling the coupling and fixing operation with the end of the rotating shaft, but has a problem in terms of weight reduction. That is, of the first and second flange portions 16d and 17d constituting the base portion 14d of the yoke 12d, the portion that suppresses the end portion of the rotating shaft in use is only the portion near the base end. On the other hand, a portion closer to the tip of the flange portions 16d and 17d has no role other than ensuring rigidity. For this reason, when it is not necessary to ensure rigidity, the presence itself causes the weight of the yoke 12d to increase. In other words, the portion closer to the tip of the flange portions 16d and 17d can be omitted as long as the rigidity necessary for the yoke, in particular, the torsional rigidity for transmitting torque can be secured, thereby reducing the weight of the yoke. Can be planned.

  FIG. 10 shows the yoke 12e previously considered from such a viewpoint. The yoke 12e is provided with first and second flange portions 16e, 17e and a discontinuous portion 18e only at a portion near the base end of the base portion 14e. In other words, a flange portion is not provided in a portion near the tip of the base portion 14e. The yoke 12e having such a structure can reduce the weight while ensuring the required rigidity unless the yoke 12e is used for transmitting a particularly large torque. For example, even in the case of a universal joint for connecting the rotating shafts constituting an automobile steering system with a power steering device, the transmitted torque is limited in the case of a universal joint incorporated on the steering wheel side from the auxiliary power source. Therefore, by using the yoke 12e as shown in FIG. 10, the weight can be reduced without causing a problem in practicality.

  However, in the case of the yoke 12e, which has been reduced in weight by the structure as described above, there is a problem in terms of ensuring the accuracy of the inner peripheral surface of the base portion 14e. That is, on the inner peripheral surface of the base portion 14a, it is necessary to form a female serration portion that engages with the male serration portion formed at the end of the rotating shaft. This female serration portion is formed as follows. First, in the process shown in FIGS. 8A to 8E, the fourth intermediate material 33a as shown in FIG. 11 having a shape corresponding to the yoke 12e shown in FIG. 10 is formed. Of the fourth intermediate material 33a, a circular hole 20b is formed at the distal end of the coupling arm portion 15b, a through hole 24 and a screw hole 25 are formed in the first and second flange portions 16e and 17e. 10) and a female spline portion is formed on the inner peripheral surface of the base portion 14e. The female spline portion is formed by broaching the inner peripheral surface of the base portion 14e after finishing the inner diameter of the base portion 14e with a cutting tool 34 such as a reamer as designed.

  In order to obtain a female spline portion having good properties (the shape and dimensions are as designed values), the inner peripheral surface of the base portion 14e is moved around the entire circumference with a tool such as a reamer or broach during the series of operations. It is necessary to scrape evenly. On the other hand, when scraping the inner peripheral surface of the base portion 14e of the fourth intermediate material 33a as shown in FIG. 11, the tip of the cutting tool 34 is in a state where the cutting tool 34 has entered the portion closer to the tip of the base portion 14e. The portion tends to fall in the direction of the arrow α in FIG. 11 toward the side where the flange portions 16e and 17e do not exist. That is, the tip of the cutting tool 34 tends to be displaced in the direction of retreating from the folded portion 35 of the base portion 14e, as exaggerated by a chain line in FIG. As a result, the engagement state between the inner peripheral surface of the base portion 14e and the cutting tool 34 becomes nonuniform in the circumferential direction, and the cutting state of the inner peripheral surface of the base portion 14e becomes nonuniform in the circumferential direction. Become. As a result, the properties of the female spline portion obtained are poor. The female spline portion with poor properties and the male spline portion formed on the outer peripheral surface of the end portion of the rotating shaft do not engage with high accuracy. Specifically, it becomes difficult to insert the end portion of the rotating shaft on the inner diameter side of the base portion 14e, or conversely, after the base portion 14e and the end portion of the rotating shaft are coupled and fixed, Shaking is likely to occur in the part.

  In view of the circumstances as described above, the present invention provides an inner peripheral surface of the base portion even when the first and second flange portions are provided only in a part of the base portion in the axial direction in order to reduce the weight. Invented in order to realize a structure capable of ensuring good properties with respect to the female spline portion formed in the above and a manufacturing method thereof.

Among the cross shaft universal joint yoke and the manufacturing method thereof according to the present invention, the cross shaft universal joint yoke described in claim 1 is similar to the above-described conventionally known cross shaft universal joint yoke. A base and a pair of arms.
Among these, the base portion is formed with a female spline portion on the inner peripheral surface for coupling and fixing the end portion of the rotating shaft, and the first and second portions sandwiching a discontinuous portion provided at one place in the circumferential direction. Both flange portions are provided, and attachment holes are provided in portions where these flange portions are aligned with each other.
Further, the both arm portions extend in the axial direction of the base portion from the diametrically opposite position at one end edge in the axial direction of the base portion.

In particular, in the universal joint yoke according to the present invention, both the flange portions are provided only in one half of the base in the axial direction away from the both arm portions. It is not provided in the other half part in the axial direction on the side close to the part.
Further, the inner diameter of the portion of the inner peripheral surface of the base where the phase in the axial direction coincides with the other half of the axial direction is larger than the inner diameter of the portion that also coincides with the half of the axial direction.
And the said female spline part is provided only in the part in which the phase regarding an axial direction corresponds to the said axial direction piece half part among the internal peripheral surfaces of the said base.

According to a second aspect of the present invention, there is provided a method for manufacturing a yoke for a cross shaft type universal joint, wherein the universal joint according to the present invention has the structure as described above by subjecting a metal plate to press working including punching and bending. A manufacturing method for manufacturing a yoke for use, comprising a first step to a fourth step.
In the first step, a metal plate is stamped and formed from two positions separated from each other in the length direction of the substrate portion of the substrate portion in the width direction of the substrate portion. A base plate provided with a pair of tongue-shaped portions protruding laterally in the width direction is formed.
And this base plate made by said 1st process WHEREIN: The part located between these both tongue-shaped parts among the width direction one end edges of the said board | substrate part WHEREIN: These both tongue-shaped parts are located rather than a part near both ends. Position it closer to the tip. And the width dimension of the length direction intermediate part of the said board | substrate part is made larger than the width dimension of the length direction both ends. Further, a relief recess is provided in a portion near one edge of the width direction in one side of the portion located between the two tongue-like portions at the intermediate portion in the longitudinal direction of the substrate portion.
In the second step, after the base plate is formed in the first step, both end portions of the substrate portion that protrude from the both tongue-shaped portions are the intermediate portions in the longitudinal direction of the substrate. Fold each 180 degrees to the one side which is the same direction with respect to the thickness direction of the part. Then, a pair of overlapping portions each having a thickness of two of the metal plates is formed.
Further, in the third step, after the second step, the portion between the two tongue-like portions is folded back into a U shape at the intermediate portion in the longitudinal direction of the substrate portion with the one surface side as the inner peripheral surface side. And the base part which provided both the 1st and 2nd flange part is formed on both sides of the discontinuous part provided in one place of the circumferential direction.
Furthermore, in the fourth step, a female serration portion is formed on the inner peripheral surface of the base portion after the third step.

  According to the cross shaft universal joint yoke of the present invention configured as described above and the manufacturing method thereof, the first and second flange portions are provided only on a part of the base portion in the axial direction in order to reduce the weight. With the provided structure, the accuracy of the female spline portion formed on the inner peripheral surface of the base portion can be ensured. That is, in the case of the yoke for a cross shaft type universal joint according to the present invention and the method for manufacturing the same, a relief recess exists in a portion of the base portion that is disengaged from the flange portions. For this reason, in the part which remove | deviated from these both flange parts, in order to form the said female spline part, the cutting tool which scrapes off the internal peripheral surface of the said base will be in the state which is not restrained over the perimeter. For this reason, the cutting tool does not incline in the direction of retreating from the folded portion of the base at the part detached from the both flanges, and the inner peripheral surface of the base is made all around by the cutting tool. Can be processed uniformly. As a result, the properties of the female spline portion formed on the inner peripheral surface of the base portion can be improved, and the engagement state between the female spline portion and the male spline portion formed at the end of the rotating shaft can be improved. .

The perspective view of the base plate manufactured by a 1st process in one example of embodiment of this invention. The figure equivalent to the II cross section of (A) of FIG. 3 which shows the process for forming a female serration part in a base. A front view (A) seen from the side of the discontinuous part showing the completed yoke, and two examples of the range where the relief recesses are formed, respectively (B) and (C) seen from above (A) . The partial cutting side view which shows an example of the steering device for motor vehicles incorporating the cross-type universal joint. The partially cut side view which shows the 1st example of the cross-shaped universal joint conventionally known. The perspective view which shows the 2nd example in the state which took out only the yoke. The figure equivalent to the roll cross section of FIG. 5 which shows the state (A) before assembling | attaching a bolt after inserting a rotating shaft in this yoke simple substance, and the state (B) after assembling | attaching a bolt. The figure which shows the manufacturing method of this yoke in order of a process. A front view (A) of the example of the yoke considered in order to secure the axial displacement between the yoke and the rotating shaft, as viewed from the discontinuity side, and a side view as viewed from the right side of (A) Figure (B). The same figure as FIG. 9 which shows an example of the structure which shortened the dimension of the flange part for weight reduction. The same figure as FIG. 2 for demonstrating the problem which arises when the dimension of a flange part is shortened.

  1 to 3 show an example of an embodiment of the present invention. In the case of this example, in the first step of the press yoke manufacturing process corresponding to FIG. 8A described above, a punching process is performed on a metal plate such as a steel plate that can obtain the required strength and rigidity. By performing press working including this, a base plate 28a as shown in FIG. 1 is formed. The base plate 28a includes a substrate portion 26a and a pair of tongue-like portions 27 and 27. These tongue-like portions 27 and 27 are respectively separated from each other in the width direction (upper edge in FIG. 1) of the substrate portion 26a in the length direction (left and right direction in FIG. 1) of the substrate portion 26a. It is formed in a state protruding from the position to the side in the width direction of the substrate portion 26a (upward in FIG. 1).

  In addition, the base plate 28a has an intermediate portion 36 located between the two tongue-like portions 27, 27 in one end edge in the width direction of the substrate portion 26a, which is longer than the two tongue-like portions 27, 27. They are positioned closer to the tips of these tongues 27 and 27 (upward in FIG. 1) than both end portions 37 and 37 existing at the portion near the direction edge. On the other hand, the other end edge in the width direction of the substrate portion 26a (the lower end edge in FIG. 1) has the same position in the width direction except for the notch portions 38 and 38 provided for facilitating the folding operation. It is said. Accordingly, the width dimensions W and w of the substrate portion 26a are large (W) at the middle portion in the length direction and small (w) at both ends in the length direction. In particular, the width dimension W of the intermediate portion in the longitudinal direction is sufficiently increased so that the above-described possible stroke amount can be sufficiently secured. On the other hand, the width dimension w of the portion closer to the edge in the length direction than the both tongue-like portions 27, 27 is stopped as much as possible to secure the coupling strength between the obtained yoke 12f and the end of the rotating shaft. To reduce weight. That is, it is obtained by processing the base plate 28a by omitting the surplus portions 39, 39 shown by the chain line in FIG. 1 (the portion that becomes the surplus portion 39a shown by the chain line in FIG. 2 when left). The yoke 12f can be reduced in weight.

  Further, a relief recess 40 is formed in a portion of the intermediate portion 36 of the substrate portion 26a in the width direction. That is, the escape recess 40 is formed in a state in which the intermediate portion 36 is biased toward a portion near the edge on the side where the tongues 27 and 27 are formed. Of the intermediate portion 36, the width dimension of the portion outside the escape recess 40 is substantially the same as the width dimension w of the portion closer to the edge in the longitudinal direction than the both tongue-like portions 27, 27.

  The base plate 28a as described above is subjected to a predetermined bending process by a press in the order shown in (A) → (B) → (C) → (D) → (E) of FIG. The fourth intermediate material 33b shown in FIG. Of the fourth intermediate material 33b, the circular hole 20b is formed at the distal end of the coupling arm portion 15b, the through holes 24 and the screw holes 25 are formed in the first and second flange portions 16e and 17e. 3), and a female spline portion is formed on the inner peripheral surface of the base portion 14e as in the case described with reference to FIG. That is, after the inner diameter of the base portion 14e is finished as designed by a cutting tool 34 such as a reamer, the inner peripheral surface of the base portion 14e is broached to form the female spline portion.

  In the case of this example, of the fourth intermediate material 33b to the base portion 14e constituting the completed yoke 12f, the portion in which the phase in the axial direction is out of the first and second flange portions 16e and 17e. The inner diameter is larger than the inner diameter of the portion corresponding to both the flange portions 16e and 17e. That is, a relief recess 40a formed on the basis of the relief recess 40 of the base plate 28a exists in a portion of the base portion 14e where the phase in the axial direction deviates from the flange portions 16e and 17e. Accordingly, in order to form a female spline portion on the inner peripheral surface of the base portion 14e, when a cutting tool 34 such as a reamer is inserted inside the base portion 14e as shown in FIG. The portion where the phase in the axial direction coincides with the flange portions 16e and 17e is engaged with the inner peripheral surface of the base portion 14e over almost the entire circumference except for the discontinuous portion 18e (see FIG. 3). (This inner peripheral surface is cut).

  That is, in the case of this example, during the step of forming the female spline portion on the inner peripheral surface of the base portion 14e, the relief shown by the oblique lattice in FIG. 3 is axially disengaged from the flange portions 16e and 17e. Due to the presence of the recess 40a, a portion of the cutting tool 34 that is axially disengaged from both the flange portions 16e and 17e does not contact any portion over the entire circumference. In short, the cutting tool 34 is formed on the surface to be processed over almost the entire circumference except for the portion facing the discontinuous portion 18e at the portion where the phase in the axial direction coincides with the two flange portions 16e and 17e. It contacts the inner peripheral surface of the base portion 14e. Further, the width δ {(B) (C)} of FIG. 3 in the circumferential direction of the discontinuous portion 18e is much smaller than the diameter D (see FIG. 2) of the cutting tool 34 (δ << D). The cutting tool 34 is not retracted into the discontinuous portion 18e. Therefore, a force that moves the cutting tool 34 in any direction with respect to the radial direction does not act at a portion where the phase in the axial direction coincides with the flange portions 16e and 17e. On the other hand, in the part where the phase in the axial direction is out of the two flange portions 16e and 17e, it does not contact any surface over the entire circumference. For this reason, even if the phase with respect to the axial direction deviates from the flange portions 16e and 17e, the force for moving the cutting tool 34 in any direction with respect to the radial direction does not act.

  As a result, the central axis of the cutting tool 34 is not inclined with respect to the central axis of the base portion 14e at any portion with respect to the axial direction, and the cutting tool 34 causes the inner peripheral surface of the base portion 14e to move around the entire circumference. Can be processed uniformly. As a result, the properties of the female spline portion formed on the inner peripheral surface of the base portion 14e can be improved, and the engagement state between the female spline portion and the male spline portion formed at the end of the rotating shaft can be improved. . After the end of the rotating shaft and the base portion 14e are easily spline-engaged, and after the spline is engaged, the bolt 22c {see FIG. 7B) screwed into the screw hole 25 is tightened. In this state, the joint between the end of the rotating shaft and the base 14e can be prevented from rattling.

  It should be noted that a range in the circumferential direction of the relief recess 40a provided on the inner circumferential surface of the base portion 14e is sufficient if it is substantially equal to or greater than a semicircular circumference. That is, as shown at least in FIG. 3 (B), if it is formed in a substantially semicircular portion located on the opposite side in the radial direction of the flange portions 16e, 17e, the cutting made to enter the inner diameter side of the base portion 14e. Applying a radial force to the tool 34 (see FIG. 2) can be suppressed to such a level that there is no practical problem. However, preferably, as shown in FIG. 3 (C), out of the inner peripheral surface of the base portion 14e, it is axially disengaged from both the flange portions 16e and 17e and rubs against the outer peripheral surface of the cutting tool 34. A relief recess 40a is formed in the entire portion to be obtained. In this way, if the relief recess 40a is formed in a wide range, it is possible to almost completely suppress the radial force from being applied to the cutting tool 34.

  Of the yoke for a cross joint universal joint according to the present invention and the manufacturing method thereof, the invention of the manufacturing method described in claim 2 is limited to a press yoke formed by pressing a metal plate. Yes. However, the invention of the object described in claim 1 is not limited to the press yoke, and a so-called forged yoke obtained by subjecting a metal material to plastic working by forging is also a technical invention of the invention of the invention. Belongs to the range. That is, even in the case of a forged yoke, it is conceivable to adopt a shape similar to that of FIG. 10 described above in order to achieve both the securing of the relative displacement amount in the axial direction of the yoke and the rotating shaft and the reduction in weight. Further, even in the case of a forged yoke, the problem described with reference to FIG. 11 described above is required when drilling to finish the inner diameter of the base to a predetermined dimension or broaching to form a female spline portion on the inner peripheral surface. Produce.

  Therefore, in the case of the forged yoke, as shown in FIGS. 2 to 3, the problem described with reference to FIG. 11 can be obtained by forming a relief recess in the inner peripheral surface of the base portion near the connecting arm portion. Can be resolved. Forming such a relief recess by forging can be easily carried out only by matching the shape of the forging die to it, as long as the shape to be obtained (forming the relief recess in a predetermined portion) is determined. In other words, in the case of a forged yoke, it is not necessary to devise the manufacturing method as in the case of a press yoke, with respect to providing the relief recess. Therefore, the manufacturing method related to the forged yoke is not particularly described in the claims. However, regarding the yoke having the shape described in claim 1, even a forged yoke belongs to the technical scope of the invention described in claim 1.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering gear unit 3 Input shaft 4 Tie rod 5 Steering shaft 6 Steering column 7 Universal joint 8 Intermediate shaft 9 Universal joint 10 Electric motor 11 Universal joint 12a, 12b, 12c, 12d, 12e, 12f Yoke 13 Cross shaft 14a, 14b, 14c, 14d, 14e Base portion 15a, 15b Connecting arm portion 16a, 16b, 16c, 16d, 16e First flange portion 17a, 17b, 17c, 17d, 17e Second flange portion 18a, 18b, 18c, 18d, 18e Continuous part 19a, 19b Rotating shaft 20a, 20b Circular hole 21a, 21b Radial bearing 22a, 22b, 22c Bolt 23a, 23b Nut 24 Through hole 25 Screw hole 26, 26a Substrate part 27 Tongue part 28, 28a Base plate 29 Overlap Matching portion 30 First intermediate material 31 Second intermediate material 32 Third intermediate material 33, 33a, 33b Fourth intermediate material 34 Cutting tool 35, 35a Turn-up portion 36 Intermediate portion 37 Both end portions 38 Notch portion 39, 39a Excess portion 40 40a relief recess

JP-A-8-284968 Japanese Patent Laid-Open No. 10-2343 JP 2000-320564 A JP 2004-223616 A Japanese Patent Publication No.7-88859

Claims (2)

  In order to connect and fix the end of the rotating shaft, a female spline portion is formed on the inner peripheral surface, and first and second flange portions are provided across a discontinuous portion provided at one place in the circumferential direction. A base portion provided with attachment holes in the mutually aligned portions of both flange portions, and a pair of arm portions extending in the axial direction of the base portion from a diametrically opposite position at one axial end edge of the base portion. In the universal joint yoke, the two flange portions are provided only on one half of the base portion on the side away from the both arm portions, and on the side close to the both arm portions. The inner diameter of the inner peripheral surface of the base portion where the phase in the axial direction coincides with the other half portion in the axial direction also coincides with the other half portion in the axial direction. The female spline portion is larger than the inner diameter of the base portion. Universal joint yoke phase in the axial direction, characterized in that it is only provided in a portion that matches said axially piece halves. In order to manufacture the universal joint yoke according to claim 1 by performing press working including punching and bending on a metal plate,
By stamping and forming the metal plate, the substrate portion protruded laterally in the width direction of the substrate portion from two positions separated in the length direction of the substrate portion among the edge in the width direction of the substrate portion. A first step of forming a base plate with a pair of tongues;
The base plate produced in the first step is located closer to the ends of the tongues than the ends closer to both ends of the widthwise end edge of the substrate part. By making the width dimension of the intermediate portion in the longitudinal direction of the substrate portion larger than the width dimension of both end portions in the longitudinal direction, the substrate portion is positioned between the two tongue-shaped portions at the intermediate portion in the longitudinal direction of the substrate portion. Of the one side of the part to do is provided with a relief recess in the width direction one end edge portion,
After the base plate is formed in the first step, in the second step, both end portions of the substrate portion that protrude from the both tongue-shaped portions are the substrate portions in the respective lengthwise intermediate portions. Each of which is folded 180 degrees on the one surface side which is the same direction with respect to the thickness direction of each, forming a pair of overlapping portions each having a thickness of two sheets of the metal plate,
In a third step performed after the second step, a portion between the two tongue-like portions at the intermediate portion in the lengthwise direction of the substrate portion is folded back into a U shape with the one surface side as the inner peripheral surface side, Forming a base provided with both first and second flange parts across a discontinuous part provided in one place in the circumferential direction,
A method for manufacturing a universal joint yoke, wherein a female serration portion is formed on an inner peripheral surface of the base portion in a fourth step performed after the third step.

Images