JP2006218513A - Method for producing pipe and pipe produced with the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a pipe by which an inner spline part can be formed with keys and key-ways having high molding precision. <P>SOLUTION: In the method for producing the pipe, by which an upper shaft 2 for shaft, is produced by forming the inner spline 21 constituted of a plurality of key-ways 21a and a plurality of keys 21b in the length direction on the inner peripheral surface at one side of the upper shaft, a swaging mandrel for forming the above key-ways 21a and the keys 21, is inserted into the inner part of the pipe from the one end part, the outer spline 12 is formed by allowing a plurality of swaging dies having cylindrical pressed surface formed in the inside while they are combined adjacent to each other, to repeat a pressing for striking and drawing the upper shaft 2 toward the center from the state of being mutually expanded at the same interval, and an opening for separating each swaging die into the state of being expanded from the upper shaft 2, and a rotation for rotating each swaging die at a fixed angle to the circular direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pipe manufacturing method for manufacturing, for example, a pipe-like upper shaft constituting a steering shaft of an automobile using a plastic metal pipe.

  In order to ensure the safety of the driver in the event of a collision, the impact energy can be absorbed by a steering shaft for transmitting steering operation to the tire. The steering shaft is composed of an upper shaft and a lower shaft. The inner surface of the upper shaft opposite to the steering wheel has an inner spline portion composed of a key and a key groove, and an outer spline portion provided on the outer periphery of the lower shaft. The resin is filled between the lower shaft and inserted into the inner spline portion of the upper shaft.

  Here, when the inner spline is formed by punching, which is a conventional general forming method, since the pipe to be formed extends in the punching direction, the forming accuracy of the keys and key grooves constituting the inner spline However, there is a problem that the clearance between the fitting portions is increased and the rotational direction error of the steering shaft is increased.

  Therefore, it has been proposed to inject resin between each key and key groove of the inner spline part and the outer spline part to reduce the gap between the fitting parts and reduce the rotational direction error as the steering shaft. (See Patent Document 1).

  However, in the above proposal, when inserting the inner spline portion and the outer spline portion, it is necessary to inject the resin between each key and the key groove, and it is difficult to reduce the manufacturing cost.

JP 2004-66970 A

    An object of the present invention is to provide a pipe manufacturing method capable of forming an inner spline portion with a key and a key groove with high forming accuracy.

  The present invention is a pipe manufacturing method for manufacturing a pipe for a shaft by forming an inner spline portion composed of a plurality of keys and key grooves in the length direction on one inner peripheral surface of the pipe, the pipe and the key, A plurality of outer dies that form a cylindrical inner press surface in the state where a core die for forming a keyway is inserted into the pipe from one end and combined next to each other are spaced apart from each other at the same interval. A press that strikes the pipe toward the center at the same time from the spread state, an opening that separates the outer shape molds from the pipe and a rotation that rotates the outer shape molds by a certain angle in the circumferential direction. It is a pipe manufacturing method which repeats these and shape | molds the said inner spline part, It is characterized by the above-mentioned.

  Simultaneously repeating the press that knocks the pipe toward the center at the same time, the opening that separates the outer shape molds from the pipe, and the rotation that rotates the outer shape molds by a certain angle in the circumferential direction. Includes a cycle in which release is performed after pressing and rotation at the same time, a cycle in which rotation and release are performed at the same time after pressing, or a cycle in which rotation, press and release are performed in order.

  In addition, opening to be separated from the pipe in an expanded state includes separating to a spread state before pressing, or separating to a state smaller than the expanded state before pressing.

  Thus, since the pipe to be molded does not extend in the punching direction, the key and the key groove constituting the inner spline can be molded with high molding accuracy. Accordingly, it is possible to reduce the clearance when the pipe is spline-fitted using the inner spline portion. Therefore, when the pipe is used as the upper shaft of the steering shaft, a steering shaft with little rotational direction error can be obtained.

  Further, since a separate process or material for reducing the rotation direction error is unnecessary, the manufacturing cost of the shaft can be reduced.

  Further, the pipe outer shape of the inner spline part can be molded simultaneously with the molding of the inner spline part.

  As an aspect of the present invention, before inserting the core type into the pipe, the pipe diameter can be reduced by pushing the inner spline side of the pipe into the drawing die for drawing.

  Reduction of the pipe diameter includes reduction of the inner surface of the reduced pipe to a diameter that is substantially the same as or larger than the large diameter of the inner spline.

  Thereby, the frequency | count of the press in which a some external type | mold strikes a pipe can be reduced. Therefore, it is possible to reduce the molding time and increase the productivity compared to the case where the inner spline is molded only by a press in which a plurality of outer dies strike the pipe without reducing the diameter of the pipe. Can be reduced.

  Further, as an aspect of the present invention, the other forming die for forming the other outer shape of the pipe is opposed to the drawing die, and the pipe supplied in between is pressed by the other forming die and the drawing die. As a result, the other pipe can be formed and the diameter of one of the pipes can be reduced.

  As a result, the outer shape of the pipe opposite to the inner spline can be molded and the diameter of one of the pipes can be reduced in the same process, so that the diameter of one of the pipes is reduced in a separate process. Compared with the case, the process can be shortened, and the manufacturing cost can be reduced.

  The present invention is also characterized in that the pipe is manufactured by the above-described pipe manufacturing method.

  Thereby, the pipe provided with the inner spline part comprised by the key and keyway with a high shaping | molding precision can be obtained.

  In addition, the present invention is a steering shaft in which a pipe manufactured by the above-described pipe manufacturing method and a male pipe having an outer spline portion on one of the outer peripheral surfaces are connected by spline fitting. .

  As a result, a steering shaft having a high molding accuracy of the key and the keyway of the inner spline portion is obtained, and the clearance when the male spline outer spline portion is inserted into the inner spline portion of the upper shaft and the spline is fitted is obtained. A steering shaft that can be reduced and has a small rotational direction error can be obtained.

  Further, since a separate process or material for reducing the rotation direction error is unnecessary, the manufacturing cost of the shaft can be reduced.

  According to this invention, an inner spline part can be shape | molded with a key and keyway with a high shaping | molding precision.

An embodiment of the present invention will be described below with reference to the drawings.
The steering shaft 1 and the upper shaft 2 will be described together with FIG. 1 showing a partial front sectional view of a steering shaft 1 of an automobile and FIG. 2 showing an explanatory view of the upper shaft 2.

The steering shaft 1 includes an upper shaft 2 and a lower shaft 11.
The upper shaft 2 has, on the steering wheel side (the upper side in the drawing), a predetermined shaft portion 2a having a different diameter in the axial direction necessary for mounting the steering wheel, a pipe center portion 2b, and a lengthwise key on the inner peripheral surface. And a spline portion 2c having an inner spline 21 composed of a keyway.

Further, the lower shaft 11 includes a key groove in the length direction provided on the outer peripheral surface on the upper shaft 2 side and an outer spline 12 composed of a key, and the outer spline 12 and the inner spline 21 of the upper shaft 2 are fitted to each other. The steering shaft 1 is configured by combining them.
Thereby, the lower shaft 11 and the upper shaft 2 can transmit a rotational motion by fitting each other's key and the key groove, and slide in the length direction. By this slide, it is possible to prevent the driver's body from being struck by the steering wheel at the time of collision.

The lower shaft 11 includes two outer splines 12 that are shorter than half the length of the inner spline 21 and spaced apart in the longitudinal direction, and an outer peripheral portion 13a is formed on the shaft portion between the outer splines 12 at the outer spline 12a. A retaining ring 13 formed so as to protrude slightly from 12 large diameters (referring to the diameter passing through the top of the key) is attached.
This prevents the lower shaft 11 from falling off the upper shaft 2 due to friction between the outer peripheral portion 13a and the key of the inner spline 21.

The shaft portion 2a of the upper shaft 2 will be described in detail. The upper bearing disposing portion 27 in which two annular concave portions 26 are formed by curling from the base portion having a large diameter toward the tip end, the tapered portion 25, the serrated shaft 24, the screw The parts 23 are arranged in this order.
Further, a key-lock long hole 28 is formed in a substantially middle portion of the pipe central portion 2b in the length direction.

In manufacturing the upper shaft 2, a round cylindrical pipe 30 having an appropriate thickness as shown in FIG. 2A is used as a material thereof. First, a portion corresponding to the shaft portion 2 a (FIG. 1). When a five-stage press process is performed, a portion corresponding to the spline portion 2c is drawn by a predetermined amount (hereinafter referred to as “first molding”) to form a first molded product 30a having a predetermined shape shown in FIG. To do. Then, a swaging process (hereinafter referred to as “second molding”) is performed on a portion corresponding to the spline portion 2c of the first molded product 30a to form a second molded product 30b having a predetermined shape shown in FIG.
After the completion of the second molding, the above-described serrated shaft 24, the screw portion 23, and the long hole 28 are formed in the second molded product 30b to complete the upper shaft 2 (see FIG. 1).

Subsequently, the press molding apparatus 3 will be described together with FIG. 3 showing the press molding apparatus 3 for first molding the upper shaft 2.
As shown in FIG. 3, the press molding apparatus 3 is provided with a supply portion 32 for supplying one pipe 30 as a material on one side of the apparatus main body 31, and taking out the first molded product 30a on the other side. The robot hand 33 is provided and is controlled by the control unit so as to be driven in synchronism with the apparatus main body 31. In the figure, 34 and 35 are operation panels, 36 is a molded product tray, and 37 is a pressure gauge of five hydraulic cylinders to be described later.

The supply unit 32 described above includes a hopper 38 that houses the pipe 30, a carry-out belt 40 that takes out the pipe 30 from the hopper 38 onto the locking unit 39 one by one, and grips the pipe 30 that has been carried out to a predetermined position. It is comprised with the supply robot hand 41 to supply.
On one side of the hopper 38, there is provided a slide plate 38a for aligning the pipes 30 that are slid to the left and right according to the length of the material pipe 30.

  The take-out robot hand 33 is set so as to grasp the first molded product 30a discharged to a predetermined position and convey it to the molded product tray 36 described above.

  A rotation table 43 is provided inside the apparatus main body 31, and the supply robot hand 41 supplies the pipe 30 and the take-out robot hand 33 takes out the first molded product 30a.

Next, the apparatus main body 31 will be described together with FIG. 4 showing a perspective view of the rotary table 43 and FIG. 5 showing an explanatory view of the main part of the press molding apparatus 3.
The apparatus main body 31 is provided with a rotary table 43 (see FIG. 4) that intermittently rotates on the bed 42 and five movable molds 45 a to 45 e that are disposed at predetermined positions above the rotary table 43 and are lowered by a hydraulic cylinder 44. (See FIG. 5), a knockout bar 48 (see FIG. 5) protruding upward from below the bed 42 by a hydraulic cylinder (not shown), an appropriate air supply means for mold cleaning, and the pipe 30 And an appropriate confirmation sensor for detecting the posture of the first molded product 30a and an appropriate torque detecting means for detecting the rotational torque of the rotary table 43. The confirmation sensor is mounted on the supply unit 32 (FIG. 3) side and the take-out robot hand 33 side.

  The rotary table 43 described above has a disk shape and rotates intermittently around the rotation center 51, and seven mold ridges 50 are placed and fixed on the peripheral edge at equal intervals. Then, seven processing stations S <b> 1 to S <b> 7 are provided on the outer periphery of the rotation center 51 of the bed 42 that rotatably supports this in correspondence with the mold cage 50 of the rotary table 43. The bed 42 does not rotate.

The above-mentioned seven processing stations S1 to S7 are sequentially supplied from the upper side, supply station S1, first press station S2, second press station S3, third press station S4, fourth press station S5, and fifth press station S6. , Take-out station S7.
The supply station S1 can be moved as close as possible to the supply section 32 and the take-out station S7 can be as close as possible to the take-out robot hand 33, or the robot hands 33 and 41 can move smoothly. The position is set as appropriate. Further, as shown in FIG. 4, the above-described knockout bar 48 protrudes upward from the bottom of the bed 42 from the above-described take-out station S7. Further, a guide bush 55 as shown in FIG. 10 is attached to the bed 42 of the take-out station S7.

The aforementioned knockout bar 48 is driven by a hydraulic cylinder (not shown), and is formed in a cylindrical shape having substantially the same diameter as the spline portion 2c of the first molded product 30a. Although the cylinder rod of the hydraulic cylinder may be used as the knockout bar 48, the knockout bar 48 is provided separately from the hydraulic cylinder because the knockout stroke and the like need to be changed according to the type and size of the first molded product 30a. It is preferable to make it replaceable.
The knockout bar 48 is set so that it retracts when it is not in operation and its upper end surface is located in the above-described guide bush 55 (FIG. 10).
In FIG. 5, 49 is a table presser.

  The rotating means 55 for intermittently rotating the rotary table 43 described above may be constituted by an appropriate intermittent rotating mechanism using a motor or a fluid cylinder, but as shown in FIG. 6, a turret 57 with a cam follower having an output shaft 56. The roller gear cam 58 for inputting rotational force to this is preferable because there is almost no vibration during rotation.

  Briefly, seven cam followers 59 are axially supported on the outer peripheral surface of the disc-shaped turret 57 with a cam follower, and the roller gear cam 58 has a groove 60 composed of a straight portion 60a and a skew portion 60b. Each cam follower 59 described above travels in the groove 60 and rotates the turret 57 with a cam follower. The output shaft 56 does not rotate when the cam follower 59 is traveling on the straight portion 60a, but is rotated when traveling on the curved portion 60b.

Subsequently, the fixed mold 61 and the movable molds 45a to 45e will be described together with FIG. 7 showing a cross-sectional view showing the first movable mold 45a and the fixed mold 61 in a released state.
In each mold cage 50 described above, the same fixed mold 61 that presses the pipe 30 in cooperation with the above-described movable molds 45a to 45e is housed.
As shown in FIG. 7, the fixed mold 61 includes a first fixed mold 62, a second fixed mold 63, and a third fixed mold 64, and the upper part of the second fixed mold 63 located at the lower portion is a tapered surface having an inverse taper shape. 65 is formed. The first fixed mold 62 is formed with a circular recess 66 and a fitting portion 67 in order to mold an intermediate portion of the first molded product 30a. Then, the movable molds 45a to 45e are sequentially fitted into the fitting part 67 on the upper part of the first fixed mold 62, thereby forming the shaft part 2a of the first molded product 30a. The fixed mold 61 is arranged so that all the fixed molds 61 are directed in the same direction with respect to the rotation center, in other words, the fixed mold 61 is centered on the virtual radiation extending from the rotation center. Regardless of the processing station S1 to S7 where the mold 61 is located, the pipe 30 being processed can be processed in the same direction.

The aforementioned movable dies 45a to 45e are arranged in order of processing corresponding to the order of the press stations S2 to S6, and are arranged so as to correspond to the fixed dies 61 located in the press stations S2 to S6. The movable molds 45a to 45e are independently lowered by separate hydraulic cylinders 44, and the pressures of these hydraulic cylinders 44 are displayed on the pressurization pressure gauge 37 (FIG. 3) described above, and individually. Pressure adjustment is possible.
Although each of the movable molds 45a to 45e will be described later, the five movable molds 45a to 45e may be lowered at the same time, but it is possible to prevent a concentrated load from being applied to the rotary table 43 by shifting the timing. This is preferable because it is possible.

  Further, the supply unit 32, the take-out robot hand 33, the knockout bar 48, and the hydraulic cylinder 44 that descends the movable molds 45a to 45e independently are driven in synchronization with the intermittent rotation of the rotary table 43. I have control. That is, the pipe 30 as the material is put into the fixed mold 61 when a certain mold cage 50 stops in the supply station S1, and the movable molds 45a to 45e when each mold cage 50 stops at each press station S2 to S6. Is lowered and stopped at the take-out station S7, the knockout bar 48 is driven and the take-out robot hand 33 is set to take out the first molded product 30a.

  Further, the above-described air supply means is set to clean the fixed mold 61 and the movable molds 45a to 45e after the first molded product 30a is taken out, and the above-described confirmation sensor detects an abnormality such as loading. In the case and when the above-described torque detecting means detects over torque, each part is stopped.

  Next, a process of forming the first molded product 30a using the press molding apparatus 3 will be described with reference to FIGS. 3, 5, and 7 to 11. FIG.

  First, as shown in FIG. 8, in the supply station S <b> 1, the single pipe 30 grasped by the supply robot hand 31 (FIG. 3) of the supply unit 32 (FIG. 3) is put into the fixed mold 61. At this time, if the confirmation sensor does not recognize an abnormality in the posture of the pipe 30, the rotary table 43 rotates, and the mold cage 50 moves to the next first press station S2, and further to the second press station S3, the third press station. It moves to press station S4 sequentially and a predetermined press work is performed. The above-described supply unit 32 performs the same operation repeatedly.

  In each of the press stations S2 to S6, the movable molds 45a to 45e are respectively lowered, so that the pipe 30 is subjected to the first molding for performing the first drawing of the shaft portion 2a and the spline portion 2c (see FIG. 9).

  In the first press station S2 to the fifth press station S6, each of the movable molds 45 of the first movable mold 45a to the fifth movable mold 45e descends independently at each station (FIGS. 7, 8, and 11). The pipe 30 is pushed into the fixed die 61 to form the outer shape of the spline portion 2c, and the outer shape of the shaft portion 2a is formed by each movable die 45 (see FIG. 1).

  Subsequently, in the take-out station S7, the knockout bar 48 is pushed up from the bottom of the rotary table 43 in the fixed mold 61 by driving the hydraulic cylinder in synchronization with the stop of the rotary table 43 (see FIG. 10). The first molded product 30 a pushed upward by the knockout bar 48 is gripped by the take-out robot hand 33 waiting above the mold cage 50 and discharged to the molded product tray 36. The movable dies 45a to 45e and the fixed die 61 are appropriately cleaned by air supply means.

  As described above, when the pipe 30 as the material is supplied into the fixed die 61 on the rotary table 43, the predetermined press working by the movable dies 45a to 45e is performed as the process proceeds to the lower press stations S2 to S6. The molding is completed. The first molded product 30a that has been molded is taken out at a further lower take-out station S7. This series of processes is sequentially and repeatedly performed on one rotary table 43.

  Therefore, as shown in FIG. 2B, the spline portion 2c can be narrowed by a predetermined amount together with the shaping of the shaft portion 2a of the upper shaft 2. As a result, the apparatus installation space can be reduced as compared with the case where the molding of the shaft portion 2a of the upper shaft 2 and the drawing processing of the spline portion 2c are performed by another apparatus, and the requirement for the first machining is required. Since the time can be shortened, the manufacturing cost can be reduced.

  Next, with respect to the swaging machine 4 that performs the second processing, FIG. 12 is a perspective view of the swaging machine 4 that performs the second molding on the portion corresponding to the spline portion 2c of the first molded product 30a. FIG. 13 shows a cross-sectional view of the vicinity, FIG. 14 shows a front view of the pipe holding portion 74, FIG. 15 shows a front view of the swaging portion 75, FIG. 16 shows an explanatory view of the swaging die 76, and FIG. A description will be given with FIG. 17 showing a side view.

  The swaging machine 4 includes a supply unit (not shown), an operation panel 71, a supply conveyor 72, a slide hand 73, a pipe holding unit 74, a swaging die 76 and a swaging mandrel 77 inside. 75, an unloading conveyor 79, an appropriate unloading unit, and an appropriate power unit and an appropriate control unit.

  As shown in FIG. 18 (a), a swaging machine is used to convey the first molded product 30a supplied by a supply unit (not shown) from the supply unit to a predetermined position where the slide hand 73 picks up the first molded product 30a. A supply conveyor 72 in the length direction is arranged on the side of 4.

  The slide hand 73 includes a grip 73a for gripping the first molded product 30a, a foldable arm 73b having a grip 73a at one end, and a slide rail 73c having foldable arms 73b at both ends. It is comprised so that it may become a square shape. The gap between the supply-side grip 73a and the carry-out grip 73a is formed to be approximately half the width of the swaging machine 4 and wider than the pipe holding portion 74. Further, the folding arm 73b can hold the first molded product 30a on the supply conveyor 72 in the extended state, and the center of the first molded product 30a gripped by the grip 73a in the folded state. The center of the holding hole 74a of the pipe holding part 74 is configured to have substantially the same height.

  The pipe holding portion 74 includes a holding hole 74a on the front surface and three holding blocks 74b arranged at equal intervals on the circumference, and the first molded product 30a supplied to the holding hole 74a is held by the holding block 74b. An appropriate rotation mechanism that rotates while being held and an appropriate movement mechanism that moves in the front-rear direction (left-right direction in FIG. 13) are provided.

  Each holding block 74b moves in the radial direction synchronously and can press and hold the outer peripheral surface of the pipe center portion 2b of the first molded product 30a inserted into the holding hole 74a (see FIG. 14). ).

The swaging portion 75 includes a through-hole 75a (see FIG. 15) on the pipe holding portion 74 side, a swaging mandrel 77 in front of the through-hole 75a (left side in FIG. 13), and a radially outer side of the swaging mandrel 77. Swaging dies 76, and respective support portions and drive portions.
Note that four swaging dies 76 are used as a set. As shown in FIG. 16, each swaging die 76 is composed of a press surface 76a having an arc-shaped press surface and a base portion 76b. Moreover, the press surface 76a is comprised by the horizontal surface of a center, and the same slope provided in the both sides as shown in FIG.16 (c) which shows a center cross section, and the left-right slope from which length differs. Further, the contact surfaces 76c on both sides of the press surface 76a are formed with a 45 ° gradient, and the four swaging dies 76 are brought into contact with the adjacent contact surfaces 76c so that the press surfaces 76a face each other. When combined, as shown in FIG. 16D, the press surface 76a can form a cylindrical shape substantially the same as the outer diameter of the spline portion 2c of the second molded product 30b.

  Further, the swaging mandrel 77 includes a pedestal portion 77a and a key portion 78 as shown in FIG. The key portion 78 has a mandrel key groove 78a (FIG. 21) and a mandrel key 78b (FIG. 21) on the outer peripheral surface, and is a mold that is inserted inside to form the key groove 21a and the key 21b of the spline portion 2c. Take a role. Further, the mandrel key groove 78 a and the mandrel key 78 b of the swaging mandrel 77 are coated with TIN. This prevents the key groove 21a and the key 21b from being welded to the mandrel key groove 78a and the mandrel key 78b by swaging.

  The swaging unit 75 includes a swaging mandrel 77 and a swaging die 76, and includes an appropriate driving unit that drives each swaging die 76 in a reciprocating direction in the radial direction and an appropriate holding unit.

  Further, as described above, the swaging mandrel 77 and the swaging die 76 are each provided with an independent drive mechanism (not shown).

Further, the holding hole 74a, the through hole 75a, the swaging mandrel 77, and the swaging die 76 combined as shown in FIG. (See FIGS. 13, 15, and 18)
Next, FIG. 18 showing a plan explanatory view of the operation of the swaging machine 4 at the time of the second machining, and FIG. 19 showing a side explanatory view at the time of FIG. 18 (a) and FIG. The operation of the machine 4 will be described.

  As shown in FIGS. 18 (a) and 19 (a), the swaging machine 4 first has a grip 73a for gripping the first molded product 30a that has been first processed by the supply conveyor 72. To the supply position. After the conveyance is completed, the slide hand 73 moves to the gripping position A, extends the folding arm 73b, and grips the first molded product 30a with the grip 73a.

  As shown in FIG. 18 (b), the slide hand 73 shrinks the folding arm 73b upward while holding the first molded product 30a with the grip 73a, and the width of the swaging machine 4 from the holding position A. It moves to the release position B on the opposite side (upper side in FIG. 18). At this time, the center of the first molded product 30a held by the grip 73a and the center of the holding hole 74a (FIG. 14) of the pipe holding portion 74 are substantially the same.

  After completion of the movement of the slide hand 73, the pipe holder 74 moves from the initial position D (FIG. 14) to the front (left side in FIG. 18) until the holding position E where the first molded product 30a is inserted into the holding hole 74a by a predetermined amount. To do. After the movement is completed, each holding block 74b is synchronously slid toward the center of the holding hole 74a and presses and holds the outer peripheral surface of the pipe center portion 2b of the first molded product 30a. At this time, the next first molded product 30a is conveyed to a predetermined position by the supply conveyor 72.

  Next, as shown in FIG. 18 (c), the slide hand 73 moves to a standby position C in which half of the amount of movement from the gripping position A to the release position B is returned to the gripping position A side. At this time, a space through which the pipe holding portion 74 passes can be formed between the grip 73a on the supply side (lower side in FIG. 18) and the grip 73a on the carry-out side (upper side in FIG. 18).

  As shown in FIGS. 18D and 19B, after the slide hand 73 moves to the standby position C, the pipe holding portion 74 moves forward little by little while rotating the first molded product 30a. At this time, the rotation speed of the first molded product 30a is the same as the rotation of the swaging mandrel 77, and the moving speed of the pipe holding portion 74 is little by little.

As the pipe holding portion 74 moves, the first molded product 30a is gradually inserted into the swaging portion 75 from the tip of the spline portion 2c.
As described above, since the center of the first molded product 30a held by the pipe holding portion 74 and the centers of the through hole 75a and the swaging mandrel 77 are substantially the same, the first molded product 30a that has passed through the through hole 75a has the same center. A swaging mandrel 77 is gradually inserted inside.

  Further, when the pipe holding portion 74 further moves forward, the spline portion 2 c of the first molded product 30 a gradually passes between the swaging dies 76. At this time, the swaging mandrel 77 is rotated by the rotating means at the same speed in the same direction in synchronization with the rotation of the first molded product 30a by the pipe holding portion 74. The swaging dies 76 are reciprocally driven in the radial direction in synchronism with the respective press surfaces 76a by a drive mechanism while rotating at a high speed. Thereby, the spline part 2c is pressed by the press surface 76a.

  Further, the pipe holding portion 74 moves forward until the necessary press length of the spline portion 2c is secured, and moves backward to the holding position E after completion of the forward movement.

  After the rearward movement of the pipe holding part 74 is completed, as shown in FIG. 18E, the slide hand 73 moves to the gripping position A, and the folding arm 73b on the carry-out side is contracted upward, so that the pipe holding part 74 is moved upward. The second molded product 30b held by the grip is gripped by the grip 73a. The slide hand 73 extends the supply-side folding arm 73b, and grips the next first molded product 30a conveyed by the supply conveyor 72 with the grip 73a.

Subsequently, as shown in FIG. 18 (f), after the pipe holding portion 74 has been moved to the initial position D, the slide hand 73 moves to the release position B, and is carried out while holding the second molded product 30b. The side folding arm 73 b is extended to release the second molded product 30 b on the carry-out conveyor 79. The released second molded product 30b is conveyed by a carry-out conveyor 79 toward a carry-out unit (not shown) (right side in FIG. 18) and carried out by the carry-out unit.
By repeating the above series of operations, the swaging machine 4 performs the second process on the first molded product 30a to obtain the second molded product 30b.

  Subsequently, with regard to the swaging process in the swaging unit 75, FIG. 20 showing an explanatory diagram at the time of pressing with the swaging die 76, and the spline part 2c of the first molded product 30a and the second molded product 30b before and after the second processing. FIG. 21 showing an explanatory diagram for explaining the relationship between the cross section and the swaging mandrel 77, and FIG. 22 showing an explanatory diagram of a state where the swaging die 76 presses the spline portion 2c. FIG. 22 shows an outline of the swaging process of the swaging die 76. The rotation angle in the directions of the arrows b and c, the reciprocation amount of the arrow d, and the like are large for easy understanding. It is written.

  As shown in FIG. 20, since the swaging mandrel 77 and each swaging die 76 do not move in the direction of arrow a, the direction of arrow a of the first molded product 30a accompanying the forward movement of the pipe holding portion 74 (FIG. 19). As a result, the swaging mandrel 77 is inserted into the spline portion 2c of the first molded product 30a. Note that the spline portion 2c is reduced by a predetermined amount by the first processing. As shown in FIG. 21 (a), the drawing amount must be such that the inner surface of the spline portion 2c of the first molded product 30a has a diameter that is slightly larger than the larger diameter of the swaging mandrel 77, and a clear 80 must be provided. is there. If the clear 80 is too large, the time required for pressing by the swaging die 76 increases. Therefore, it is desirable that the clearance 80 has a gap that can absorb the movement error when the swaging mandrel 77 is inserted.

  Further, the first molded product 30a and the swaging mandrel 77 rotate in the direction of the arrow b, and each swaging die 76 rotates in the direction c opposite to the direction of the arrow b while being synchronized, and in the radial direction with respect to the rotation axis. It is reciprocatingly driven in a certain arrow d direction. Therefore, as shown in FIG. 22, the outer peripheral surface of the spline portion 2 c can be uniformly pressed with the press surface 76 a toward the center direction of the swaging mandrel 77. The arrow b direction and the arrow c direction may be opposite to the illustrated direction, and the arrow b direction and the arrow c direction may be the same direction.

  As shown in FIG. 22 (b), since the curvature of the outer peripheral surface of the spline portion 2c is larger than the curvature of the press surface 76a at the beginning of pressing, the contact surfaces 76c do not contact each other in the pressed state, and adjacent contact surfaces. A gap 76d is generated between 76c, and a protrusion 2d that is not pressed on the outer periphery of the spline portion 2c is generated (see FIG. 22B '). However, as shown in FIG. 22C, each swaging die 76 spreads in the direction of the arrow d and rotates as shown by the arrow c, and the first molded product 30a and the swaging mandrel 77 are also synchronized with the arrow. Rotate b. Therefore, as shown in FIG. 22 (d), each swaging die 76 moves again in the direction of the arrow d, and the concave portion 2d is pressed when the outer peripheral surface of the spline portion 2c is pressed by the press surface 76a. Can do.

  By repeating FIGS. 22A to 22E a predetermined number of times, the clear 80 shown in FIG. 21A is eliminated, and as shown in FIG. 21B, the outer peripheral surface of the swaging mandrel 77 and the spline portion 2c. Close contact with the surrounding surface. Therefore, the key groove 21a and the key 21b of the inner spline 21 are formed by the mandrel key groove 78a and the mandrel key 78b.

  Since the mandrel key groove 78a and the mandrel key 78b are coated with TIN as described above, the mandrel key groove 78a and the key 21b and the mandrel key 78b and the key groove 21a are not welded, and the swaging mandrel from the spline portion 2c. 77 can be pulled out easily.

Through the above steps, the second molded product 30b shown in FIG. 2C is obtained.
In the second molding, since the swaging is sequentially performed from the end of the spline part 2c, the spline part 2c can be prevented from extending in the length direction by molding the spline. Therefore, the mandrel key groove 78a and the mandrel key 78b can secure a smooth and sharp corner in each of the key groove 21a and the key 21b, and the inner spline 21 is formed by the key groove 21a and the key 21b with high molding accuracy. Can do.

  Then, by causing the inner spline 21 of the upper shaft 2 subjected to the second machining by the swaging machine 4 and the outer spline 12 of the lower shaft 11 to be spline-fitted, it is possible to expand and contract in the length direction but to reduce the rotational direction error. A small number of steering shafts 1 can be obtained.

  In addition, since a predetermined amount of drawing is performed on the spline portion 2c in the first processing, the time required for performing the swaging processing on the spline portion 2c with the swaging machine 4 can be shortened, and the second molded product The productivity of 30b can be improved.

  Further, in the first molding, the press molding apparatus 3 has the seven mold rivets 50, so that the pipe 30 can be sequentially and repeatedly subjected to the press molding one after another, and the operating efficiency is improved, and the first molded product 30a is improved. Productivity can be improved.

  Furthermore, since the fixed mold 61 is detachably housed in the mold cage 50, the fixed mold 61 and the movable molds 45a to 45e are changed, and the strokes of the movable molds 45a to 45e and the knockout bar 48 are adjusted. The shape and size of the first molded product 30a can be easily changed.

In correspondence between the configuration of the present invention and the above-described embodiment,
The pipe of the present invention corresponds to the upper shaft 2,
Similarly,
The inner spline part corresponds to the inner spline 21,
The core type corresponds to the swaging mandrel 77,
The inner press surface corresponds to the press surface 76a,
The outer shape corresponds to the swaging die 76,
The aperture type corresponds to the fixed type 61,
The other mold corresponds to the movable molds 45a to 45e,
The outer spline part corresponds to the outer spline 12,
Corresponding to male pipe, lower shaft 11,
The present invention is not limited only to the configuration of the above-described embodiment, and many embodiments can be obtained.

The side view of the upper shaft which is an example of a molded article. The side view of the pipe which is material. The perspective view of a press molding apparatus. The perspective view of a rotary table. Explanatory drawing of the principal part of a press molding apparatus. Explanatory drawing which shows an example of a rotation means. Sectional drawing which shows a 1st movable mold | type and a fixed mold | type in a mold release state. Sectional drawing which shows the process state of the back | latter stage in a supply station. Sectional drawing which shows the state in a press station. Sectional drawing which shows the state in an extraction station. Explanatory drawing of the shape of the axial part by a movable type and a movable type. The perspective view of a swaging machine. Explanatory drawing of the principal part of a swaging machine. The front view of a pipe holding part. The front view of a swaging part. Explanatory drawing of a swaging die. A side view of a swaging mandrel. Plane explanatory diagram of the operation of the swaging machine Side view of swaging machine operation Explanatory drawing of press by swaging die Explanatory drawing explaining the relationship between the cross section of a spline part, and a swaging mandrel. Explanatory drawing of the state which a swaging die presses a spline part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steering shaft 2 ... Upper shaft 11 ... Lower shaft 12 ... Outer spline 21 ... Inner spline 21a ... Key groove 21b ... Key 45a-e ... Movable type 61 ... Fixed type 76 ... Swaging die 76a ... Press surface 77 ... Swaging Mandrel

Claims (5)

A pipe manufacturing method for manufacturing a pipe for a shaft by forming an inner spline portion composed of a plurality of keys and key grooves in the length direction on one inner peripheral surface of the pipe,
A core mold for forming the key and the key groove is inserted into the pipe from one end,
A plurality of outer dies that form a cylindrical inner press surface on the inside in a state of being combined next to each other, a press that strikes the pipe toward the center at the same time from a state in which the outer shapes spread at the same interval, and
Opening each of the outer shape molds apart from the pipe in a spread state;
A pipe manufacturing method for forming the inner spline portion by repeatedly rotating each outer shape mold in the circumferential direction by a certain angle. The pipe manufacturing method according to claim 1, wherein before inserting the core mold into the pipe, the pipe diameter is reduced by pushing the inner spline side of the pipe into a drawing mold for drawing. The other mold for molding the other outer shape of the pipe is opposed to the drawing mold, and the pipe supplied in between is pressed by the other shaping mold and the drawing mold, so that the other of the pipes is pressed. The pipe manufacturing method according to claim 2, wherein the forming and the reduction of one pipe diameter of the pipe are performed.   A pipe manufactured by the pipe manufacturing method according to claim 1. A steering shaft in which the pipe according to claim 4 and a male pipe having an outer spline portion on one of the outer peripheral surfaces are connected by spline fitting.

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