JP5097757B2 - Pipe press forming method and apparatus - Google Patents

Description

  The present invention relates to a pipe press-forming method and apparatus suitable for manufacturing an upper shaft constituting a steering shaft of an automobile, for example.

  The steering shaft of the above example has a steering wheel attached to the upper end, and in order to ensure the safety of the driver's body in the event of a collision, the collision energy can be absorbed. As an example of the configuration for this purpose, there is an upper shaft to which a steering wheel is attached and a spline formed at a connecting portion of the lower shaft connected to the lower side of the upper shaft so as not to be relatively rotatable. In other words, the spline is formed on the inner peripheral surface of the lower end portion of the upper shaft, and is slidable in the longitudinal direction between the lower shaft. With this structure, it is possible to prevent the steering wheel from hitting the driver at the time of collision.

  For this purpose, the spline must be formed on the inner peripheral surface of a part of the upper shaft, and a method described in Patent Document 1 below has been proposed as a method for forming the spline.

  In this method, cold forging is performed while hitting a die that is divided on the outer peripheral surface of a pipe in a state where a core die is inserted in a portion where a spline is to be formed.

However, since the processing is performed while hitting in order, it takes time to process one pipe, and the efficiency is not good. In addition, since the apparatus is complicated, there is also a problem that equipment costs are required.

  Therefore, the main object of the present invention is to enable reduction in processing time and reduction in equipment costs.

The means for this is a method for press-forming a pipe having a throttle part having a diameter smaller than that of the other part on at least one end side in the longitudinal direction of the pipe, and having a spline on the inner peripheral surface of the throttle part. A press forming process of pressing the drawing portion by moving the mold in the longitudinal direction of the pipe is performed in a plurality of stages by each of the plurality of movable drawing molds, and between the pressing processes of each stage. While the movable drawing die used in the next-stage press forming process is moved to a position corresponding to the punch so that the next-stage press forming process can be performed, the drawing section gradually desires the press-forming process at each stage. The punch is press-fitted into the throttle portion while the pipe is constrained by the movable throttle die, and is moved forward by a processing blade formed at the tip of the punch. Of the plurality of movable diaphragm molds, the final stage of the movable diaphragm is the final stage of the press molding process in which the spline is formed in a plurality of stages and the spline forming process for forming the spline and pulling out the press-fitted punch straightly is performed. The press forming step and the spline forming step performed in a state where the pipe is constrained by a mold are performed in a longitudinal direction of the pipe by a fixed die having a shape corresponding to the other end side in the longitudinal direction of the pipe. This is a pipe press-forming method performed with the other end held .

In addition, a pipe press molding apparatus having a throttle part having a diameter smaller than that of the other part on at least one end side in the longitudinal direction of the pipe and having a spline on the inner peripheral surface of the throttle part , wherein the throttle part is pressed. A movable aperture die that moves in the longitudinal direction of the pipe to be formed is provided, and a through hole that penetrates in the moving direction of the movable aperture die is formed at the center of the movable aperture die, A punch that moves separately from the movable squeeze die is provided, and the squeezed press squeezed at the tip of the punch that moves when the movable squeeze press-presses the squeezed portion and restrains the pipe. When a working blade for press-fitting into the inner peripheral surface of the part to form the spline is provided, and a plurality of the movable draw dies are provided according to the shape of the inner peripheral molding surface so as to be press-molded in a plurality of stages. In addition, there is provided a moving means for moving the plurality of movable diaphragm dies to a position corresponding to the punch in the order in which the diaphragm portion has a desired diameter, so that the other end side in the longitudinal direction can be held. It is a press molding apparatus of the pipe provided with the fixed mold of the shape corresponding to .

  The spline is performed at a time by press-fitting a punch in synchronism with press molding by a movable drawing die. Further, at the time of press-fitting and pulling out the punch, the movable restrictor mold restrains the pipe, prevents plastic deformation of the outer peripheral surface of the pipe, and ensures that the desired spline is formed.

  As described above, according to the present invention, since the spline is formed by a single operation in synchronization with the press forming for drawing, the processing time can be shortened. In addition, since the movable diaphragm mold and the punch that passes through the movable diaphragm mold are used, the overall structure of the apparatus can be simplified and the equipment cost can be reduced.

The front view of a press molding apparatus. The partially broken front view of a steering shaft. Explanatory drawing which shows the manufacturing process of an upper shaft. Sectional drawing which shows the principal part of a press molding apparatus. The bottom view of a raising / lowering board and the top view of a stage. Front view of the punch. Sectional drawing which shows the process before the formation process of a connection part and a spline. Sectional drawing which shows the press molding state of the 1st step of the formation process of a connection part and a spline. Sectional drawing which shows the press molding state of the 2nd step of the formation process of a connection part and a spline. Sectional drawing which shows the spline formation state of the formation process of a connection part and a spline. Sectional drawing which shows the state which extracted the punch after the spline formation of the formation process of a connection part and a spline. Sectional drawing which shows the process after the formation process of a connection part and a spline.

An embodiment for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows a press molding apparatus 11, which press-molds a plastic metal pipe 12 to obtain various products and intermediate products. As an example, for example, there is an intermediate product of an upper shaft 72 constituting a steering shaft 71 of an automobile as shown in FIG.

  The upper shaft 72 has a well-known configuration, and has a steering wheel attachment portion 73 for attaching a steering wheel (not shown) to one end portion (upper side in FIG. 2) in the longitudinal direction, and the other end portion in the longitudinal direction (see FIG. 2, the connecting portion 75 for connecting the lower shaft 74 constituting the steering shaft 71 is provided.

  The steering wheel attachment portion 73 and the connection portion 75 are formed by narrowing and narrowing the corresponding part of the pipe 12. A female spline 75 a is formed on the inner peripheral surface of the connecting portion 75.

  This female spline 75a is slidable in the longitudinal direction with the male spline 74a provided at the tip of the lower shaft 74 fitted therein, preventing relative rotation of both. The occurrence of such a slide at the time of a collision can avoid the inconvenience of the driver hitting the steering wheel.

  In FIG. 2, 73a is a thread portion, 73b is a serration portion, 73c is a taper portion, 73d is an annular groove, 76 is a large diameter portion, 76a is a long hole for key lock, and 77 is a reverse taper portion.

  Such an upper shaft 72 is manufactured through a process as shown in FIG. The manufacturing process is largely divided into a primary process and a secondary process. The primary process is a pre-process for forming the steering wheel mounting portion 73 on the one end 12a of the pipe 12 into the intermediate shape 13, and a pipe. 12 can be divided into a connecting portion and a spline forming step for forming the connecting portion 75 and the female spline 75a at the other end portion 12b. In the press molding apparatus 11, a connecting portion and a spline forming step are performed, and the thread portion 73a, the serration portion 73b, the annular groove 73d, and the long hole 76a are formed by the subsequent secondary processing.

  In the connecting part and spline forming step, the connecting part 75 is press-molded with the movable diaphragm die 21 moving in the longitudinal direction of the pipe 62, and the pipe 12 is restrained with the movable diaphragm mold 21 during the press molding. The punch 31 is pressed into the connecting portion 75 as it is, the female spline 75a is formed by the processing blade 32 formed at the tip of the punch 31, and the press-fitted punch 31 is pulled out straight. From the difference between the diameter of the pipe 21 and the diameter of the connecting portion 75, specifically, the connecting portion 75 is press-molded in two stages using two movable aperture dies 21a and 21b. At the time of final press molding in the two-stage press molding, the punch 31 is press-fitted while the pipe 12 is restrained by the movable diaphragm mold 21b at the final stage of the movable diaphragm mold.

  The press molding apparatus 11 will be described. The press molding apparatus 11 includes a stage 41 and a lifting plate 51 that moves up and down with respect to the stage 41. As shown in FIGS. 4 and 5 (b), a mold cage 42 is provided at the center of the stage 41. One end of the mold cage 42 has the intermediate shape 13 (see FIG. 3). The fixed mold 43 having a shape corresponding to the pipe 12 formed in the above is accommodated.

  The elevating plate 51 is supported on a stage 41 by a guide rod 52, and is provided so as to move up and down by a predetermined stroke by a first cylinder 53 provided above.

  A slide plate 54 is slidably held on the lower surface of the elevating plate 51 facing the stage 41, and the two movable aperture dies 21a arranged in the front-rear direction are arranged on the lower surface of the slide plate 54. 21b is held. These movable aperture dies 21a and 21b are different in the shape and size of the inner peripheral surface as the molding surface because the connecting portion 75 is molded in two stages.

  The slide plate 54 moves in the front-rear direction along the guide rail 56 by driving of the slide cylinder 55 held behind the elevating plate 51. The moving range pulls the piston rod 55a of the slide cylinder 55. When one of the movable diaphragm molds 21a (first-stage movable diaphragm mold) is located at the center of the lift plate 51, and the piston rod 55a is pushed out, the other movable diaphragm mold 21b (second-stage movable diaphragm mold). The diaphragm type is set so as to be positioned at the center of the lift plate 51 (see FIG. 4). Stoppers 57 and 58 are provided at the front end and the rear end of the movement range to restrict the movement range (see FIG. 5A).

  As shown in FIG. 4, the movable aperture die 21 has a cylindrical shape having a through hole 22 in the center, and a first sheet portion 23 is formed at the upper end portion of the through hole 22 so as to expand in the outer peripheral direction toward the upper side. . Further, a through hole 54 a having the same diameter as the upper end of the first sheet portion 23 is formed at a position corresponding to the through hole 22 in the slide plate 54. A communication hole 59 that communicates with the through hole 54 a is formed at the center of the elevating plate 51. The communication hole 59 has a cylindrical hole portion 59a having the same diameter as the through hole 54a at the lower end, a second sheet portion 59b extending in the outer circumferential direction toward the upper side, and a cylindrical hole having the same diameter as the upper end of the second sheet portion 59b. It has part 59c in order from the bottom.

  The front end portion of the punch 31 is accommodated in the communication hole 59. Since the punch 31 forms the female spline 75a as described above, the punch 31 moves up and down separately from the up-and-down movement of the elevating plate 51, and via the gate-shaped support portion 60 provided on the upper surface of the elevating plate 51. The lift plate 51 is provided in a non-contact manner. That is, the second cylinder 61 is provided on the upper surface of the support portion 60, and the upper end portion of the punch 31 is fixed to the attachment member 33 at the tip end portion of the piston rod of the second cylinder 61.

  The attachment member 33 is formed in a shape capable of entering the through hole 54a and the communication hole 59, and has an inclination angle of the second sheet portion 59b so as not to come into surface contact with the second sheet portion 59b of the communication hole 59. Has contact portions 33a formed at different angles.

  As shown in FIG. 6, the punch 31 has a cylindrical portion 31b having the same diameter as that of the lower end portion of the mounting member 33, and a funnel-like shape below the cylindrical portion 31b. A contact portion 31c is formed. The contact portion 31 c is a portion corresponding to the first sheet portion 23, and is formed at an angle different from the inclination angle of the first sheet portion 23. The lower end portion of the shaft portion 31a has the working blade 32 that forms the female spline 75a by press-fitting into the inner peripheral surface of the connecting portion 75 formed by press molding with the movable diaphragm die 21.

  In order to form the female spline 75a straight and to be able to be pulled out from the pipe 12, the punch 31 having such a shape needs to be prevented from rotating horizontally during ascent and descent. Therefore, as shown in FIG. 1 and FIG. The detent means 34 includes a detent shaft 35 that stands vertically upward from the mounting member 33, and an insertion hole portion provided in the support portion 60 and the like to hold the detent shaft 35 slidably in the vertical direction. 36.

  The driving patterns of the first cylinder 53, the second cylinder 61, and the sliding cylinder 55 are controlled by a control panel (not shown).

  In order to perform the press forming of the connecting portion and the spline forming process with the press forming apparatus 11 configured as described above, the following is performed.

  First, as shown in FIG. 7, with the lifting plate 51 positioned at the raised position, the pipe 12 having the intermediate shape 13 formed at the lower end is put into the fixed mold 43 in the mold cage 42 and held. To do. Subsequently, the first cylinder 53 is driven to lower the lifting plate 51. At this time, with respect to the movable diaphragm mold 21 of the lifting plate 51, the movable diaphragm mold 21a used for the first stage diaphragm press is positioned at the center of the lifting plate 51. When the elevating plate 51 is lowered, the other end portion 12b (upper side in FIG. 8) of the pipe 12 is press-formed with the fixed die 43 in accordance with the shape of the movable aperture die 21a.

  Thereafter, the lift plate 51 is raised to release the pipe 12, while the movable squeeze die 21 is moved so that the second stage squeezing press can be performed. That is, the movable diaphragm die 21 b is positioned at the center of the lifting plate 51 using the second stage diaphragm press. When the elevating plate 51 is lowered again, the second stage of drawing press is performed as shown in FIG. Thereby, the connection part 75 of a desired shape can be formed.

  Subsequently, the movable diaphragm die 21b in the second stage is lowered, and the second cylinder 61 is driven while the pipe 12 is restrained to lower the punch 31 as shown in FIG. Then, the working blade 32 of the punch 31 is press-fitted into the inner peripheral surface of the press-formed connection portion 75. This press-fitting is performed so as to penetrate the connecting portion 75. At this time, the punch 31 is pushed straight into the inner periphery of the connecting portion 75 by the anti-rotation means 34 to form a female spline 75a that extends straight in the longitudinal direction of the pipe 21.

  Thereafter, the second cylinder 61 is driven, and the punch 31 is pulled out from the pipe 12 as shown in FIG. Since there is the anti-rotation means 34, the punch 31 can be pulled out correctly without damaging the female spline 75a.

  Finally, when the first cylinder 53 is driven to raise the elevating plate 51, the pipe 12 as an intermediate product is released and can be taken out from the mold cage 42 as shown in FIG.

  The connecting portion 75 may be formed by a single press forming. In this case, the second cylinder 61 is driven and the punch 53 is lowered during the first stage press forming by the movable die 21. It is only necessary to change the drive pattern on the control panel.

  As described above, the female spline 75a is formed while the movable diaphragm die 21 restrains the pipe 12 after the press molding by the movable diaphragm mold 21 is completed. In other words, the female spline 75a is formed in synchronization with the press molding. Therefore, compared with the case where the female spline is formed using another mold or the like, the operation is easy and the time can be shortened. Moreover, since the female spline 75a is formed at a time by the press-fitting of the punch 31, the processing is quick. Plastic deformation that erects the spline is also easy.

  Moreover, since the press molding apparatus 11 can be comprised with the raising / lowering board 51 which raises / lowers with respect to the stage 41, and the punch 31 attached to this raising / lowering board 51, it can simplify the structure of the whole apparatus and reduction of installation cost. Is possible.

In correspondence between the configuration of the present invention and the configuration of the one aspect,
The throttle portion of the present invention corresponds to the connecting portion 75,
Similarly,
The spline corresponds to the female spline 75a,
The moving means corresponds to the sliding cylinder 55,
The present invention is not limited to the configuration of the one form described above, and other forms can be adopted.

DESCRIPTION OF SYMBOLS 11 ... Press molding apparatus 12 ... Pipe 21,21a, 21b ... Movable aperture type | mold 22 ... Through-hole 31 ... Punch 32 ... Processing blade 55 ... Slide cylinder 75 ... Connection part 75a ... Female spline

Claims (2)

A press molding method for a pipe having a throttle part having a smaller diameter than the other part on at least one end side in the longitudinal direction of the pipe, and having a spline on the inner peripheral surface of the throttle part,
A plurality of movable diaphragm molds are used to perform a press molding step of press-molding the diaphragm portion by moving the movable diaphragm mold in the longitudinal direction of the pipe, and performing a plurality of stages.
During the press process of each stage, the movable drawing die used in the press process of the next stage is moved to the position corresponding to the punch so that the press molding process of the next stage can be performed, and the press molding process of each stage In order so that the throttle part gradually has a desired diameter,
A spline is formed by press-fitting a punch into the restricting portion while the pipe is constrained by the movable squeeze die, forming the spline with a machining blade formed at the tip of the punch, and pulling out the press-fitted punch straight. Of the press forming process performed over a plurality of stages, the process is performed in a state where the pipe is constrained by the movable diaphragm mold in the final stage among the plurality of movable diaphragm molds,
The press molding process and the spline forming process performed over a plurality of stages,
A method of press molding a pipe, which is performed in a state where the other end side in the longitudinal direction of the pipe is held by a fixed die having a shape corresponding to the other end side in the longitudinal direction of the pipe. A pipe press molding apparatus having a narrowed portion having a smaller diameter than the other part at least at one end side in the longitudinal direction of the pipe, and having a spline on the inner peripheral surface of the narrowed portion,
A movable diaphragm mold is provided that moves in the longitudinal direction of the pipe to press-mold the diaphragm section,
A through-hole penetrating in the moving direction of the movable diaphragm mold is formed at the center of the movable diaphragm mold,
A punch that moves in the through hole separately from the movable aperture die is provided,
The spline is formed by press-fitting into the inner peripheral surface of the press-formed throttle part at the tip part of the punch that moves when the movable die is press-molded and restrains the pipe. A processing blade is provided,
A plurality of the movable diaphragm molds are provided according to the shape of the inner peripheral molding surface so as to be press-molded in a plurality of stages,
A moving means is provided for moving the plurality of movable diaphragm dies to a position corresponding to the punch in the order in which the diaphragm portion has a desired diameter.
A pipe press molding apparatus comprising a fixed mold having a shape corresponding to the other end side so as to be able to hold the other end side in the longitudinal direction .

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