JP2007075893A - Apparatus and method for forming serration in inner part of hollow tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a product uniformly forming a serration even at near the boundary with a tapered tube without needing the excessive product cost, in the forming apparatus and the forming method for arranging the serration on the inner surface in a small diameter portion of a hollow tube. <P>SOLUTION: After performing a primary formation arranging the serration to a range coming to the boundary with the tapered tube 33 on the inner surface of a first small diameter tube 31 of the hollow tube 30, a secondary formation (finish formation) for shaping the serration generating the distortion is performed. The primary formation is performed by using a first die 280 assembled so as to be slidable in a hollow die case 210 and a core 220 for forming the serration part 221 on the outer peripheral surface at the tip end part. The secondary formation is performed by using a second die 400 having smaller inner diameter than the first die 280 to push in a mandrel 420 into the tapered tube 33 in the hollow tube 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a molding apparatus and a molding method for providing serrations in a hollow tube. In particular, the present invention relates to a serration molding device inside a hollow tube that is improved in accuracy with respect to the serration formed in the small diameter portion up to the boundary portion with the tapered portion, and the molding method thereof. .

  For example, since a large twisting force acts on the propulsion shaft of an automobile, a hollow tube having a large polar moment of inertia is used. In addition, hollow tubes that are smaller in weight than solid shafts and can resist a large twisting force are applied in many fields.

  Recently, a hollow tube has been applied to the steering shaft of automobiles to ensure the safety of the driver from the dangers associated with vehicle collisions.

  For example, a steering apparatus for an automobile is an apparatus that operates so that a traveling direction of a traveling vehicle can be switched as intended by a driver.

  Such a steering device includes an operating mechanism including a steering handle, a steering shaft, a column, etc., and a rotation of the steering shaft so that a driver can directly perform a steering operation and transmit the operating force to each mechanism. By decelerating, the operating force is increased, the gear mechanism for changing the direction of movement of the operating mechanism and transmitting it to the link mechanism, and the movement of this gear mechanism is transmitted to the front wheels, and the positional relationship between the left and right wheels is correctly maintained. A pitman arm, a drag link, a knuckle arm, a tie rod, and the like.

  The steering shaft consists of a universal joint upper link connected to the steering handle and a universal joint lower link connected to the steering gear box, but the universal joint upper and lower links are universal joints. It is connected.

  A steering column is wrapped and combined on the outer peripheral surface of the universal joint upper end link, and a tilt lever that can adjust the angle of the steering handle according to the body shape of the driver is rotatably provided. Yes.

  On the other hand, when a forward collision accident occurs while the vehicle is running, the impact force is transmitted to the steering gear box through the engine room, and the impact force transmitted to the steering gear box is transmitted to the steering handle through the steering shaft. The

  At this time, the steering gear box is pushed into the room by the impact force, and at the same time, the steering shaft and the steering handle connected to the steering gear box are pushed into the room, so the steering handle is operated. There is a risk that the person will be hit.

  For this purpose, as shown in FIG. 1, the steering shaft 2 is composed of an upper shaft 3 to which a steering handle (not shown) is assembled, a lower shaft 4 and a hollow jacket 5 connecting them. There is something.

  The lower shaft 4 is connected to the jacket 5 by a pin 6, and a steel ball 8 is press-fitted on the outer peripheral surface of the lower shaft 4, but when the lower shaft 4 is press-fitted into the jacket 5 during an impact, the steel ball 8 is The impact energy is reduced by being pushed into the inner peripheral surface of the belt 5.

  However, the upper shaft 3 used in the steering device as described above is manufactured in a rod shape to increase the weight of the vehicle body, and the jacket 5 which is a space for connecting the upper shaft 3 and the lower shaft 4 is provided. Since it must be provided, there is a problem that the assembly process increases.

  In addition, in order to manufacture the upper shaft for the steering device, a swaging machine is used in which a rotating cam struck and repeatedly struck and formed, and this involves mechanical strength of the shaft by struck at the time of molding. There is also a problem of lowering.

  FIG. 2 shows a steering device shaft 100 previously filed by the applicant of the present application due to such a problem. This is because a hollow main body 10 in which a key lock recess 20 for inserting a switch operating mechanism such as a light switch or a washer switch is formed, and a steering handle (not shown) is coupled to an outer diameter portion of one end. And an inner diameter serration 16 in which a lower shaft (not shown) is coupled to the inner diameter portion of the other end.

  The shaft 100 having such a structure makes it possible to mitigate the impact by pushing the lower shaft in the axial direction along the inner diameter serration 16 at the time of a vehicle collision.

Conventionally, in order to form a serration inside a hollow tube, the serration was formed by a broaching method, or a serration was formed using a swaging device. However, when the broaching method uses a swaging device to form serrations inside the hollow tube, there is a problem that it is expensive and the molding time is long. In particular, when a swaging apparatus is used, noise is increased during production. Further, when serration is provided inside the small-diameter tube portion of the hollow tube, elastic deformation occurs near the boundary with the tapered tube. Therefore, the serration provided in the vicinity of the boundary with the taper tube is distorted, and there is a problem that the serration becomes non-uniform.
Korean Patent Application Publication 2006-0000714 JP2002-235727 JP-A-11-247835

  The present invention has been devised to solve the above-mentioned problems, and when the serration is formed inside the hollow tube so that the other shaft smoothly enters, the manufacturing cost is low and easy. It is an object of the present invention to provide a serration molding apparatus inside a hollow tube and a molding method thereof that can mold the serration and can uniformly mold the serration formed at the boundary with the tapered tube.

  The serration forming apparatus inside a hollow tube of the present invention that achieves the above object is characterized in that a hollow die case having an opening formed at an upper end thereof is slidably coupled to the die case, and a first taper portion is formed at a central portion. A hollow first die into which the hollow tube enters, and a lengthwise direction inside the die case, and a serration portion is formed on the outer peripheral surface of the tip portion, and enters the hollow tube. A core that forms a first serration inside the hollow tube, a pressurizing means that pressurizes the hollow tube against the first die and the core, and the hollow tube is separated from the core and the first die. And an ejecting means for causing the image to be ejected.

  The pressurizing means includes a hydraulic means for supplying a hydraulic medium to the inside of the die case to generate a hydraulic pressure, and discharging the hydraulic medium; a hollow tube coupled to the first die; and a first die. A punch block that pressurizes the core, and the hydraulic pressure is applied to the hollow tube pressed against the first die while the punch block pressurizes the hollow tube to form the first tapered tube. The pressure of the punch block is set to be relatively larger than that of the punch block, and the hydraulic pressure is set to be relatively smaller than the pressure of the punch block while the hollow tube is coupled to the core to form the first serration. Features.

  The ejecting means includes a first stripper formed in a hollow shape and slidably coupled to the core; and an eject pin that pushes the first stripper in a direction in which the hollow tube is detached. To do.

  The serration forming apparatus inside the hollow tube includes a hollow second die into which the hollow tube formed with the first serration enters, a punch block that presses and presses the hollow tube into the second die, A mandrel which is provided inside the second die so as to be movable up and down, has serrations formed on the outer peripheral surface of the tip, and enters the hollow tube; a second stripper which is slidably coupled to the mandrel; and An eject pin for ejecting the hollow tube from the mandrel in conjunction with a stripper, and an elastic means for elastically biasing the mandrel in the eject direction of the hollow tube are further provided.

  The second die is characterized in that a second taper portion having a smaller diameter than the first taper portion of the first die is formed.

  The method for forming serrations in the hollow tube of the present invention is a shape corresponding to the first die by pressing the hollow tube to be formed on the first die formed with the desired small diameter portion, large diameter portion and taper portion. And forming a first serration on the inner surface of the first small-diameter tube of the hollow tube until the boundary between the first small-diameter tube and the first taper tube is formed. Pressing the hollow tube formed with the first serration against a second die having a taper portion relatively smaller than the taper portion of the first die, and the mandrel formed with the serration is attached to the hollow tube And a secondary forming step of discharging after being pushed into the tapered tube.

  According to the serration forming apparatus and the forming method for a hollow tube according to the present invention, the serration is formed on the inner surface of the first small-diameter tube of the hollow tube up to the portion reaching the boundary with the taper tube, and then the distorted serration 2 By shaping and finishing in the next molding, the serration accuracy in the tapered tube 33 portion is improved. As a result, the entry of the mating shaft combined with the hollow tube can be made smooth, and the rigidity of the hollow tube 30 can be improved.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  A hollow tube according to an embodiment of the present invention has a structure in which a rotational force is transmitted to a mating shaft coupled thereto, and the mating shaft can smoothly enter the hollow tube.

  Such a hollow tube is, for example, in a steering device of an automobile, in which a steering handle is coupled to one end of the hollow tube and the other shaft is coupled to the other end of the hollow tube. By allowing the opposite shaft to enter the inside of the hollow tube, the impact can be absorbed to protect the driver from accidents.

  The hollow tube forming process will be described with reference to FIGS. 3a to 3c. The hollow tube of an Example has the structure shape | molded as follows. First, in the hollow circular hollow tube 30 of FIG. 3A, as shown in FIG. 3B, a first small-diameter tube 31, a large-diameter tube 32 expanded from the first small-diameter tube 31, and the first small-diameter tube 31 It shape | molds so that it may have the 1st taper pipe | tube 33 which connects the large diameter pipe | tube 32. FIG. Next, as shown in FIG. 3 c, the first serration 34 is formed in the first small-diameter pipe 31.

  The first serration 34 is formed from the first small-diameter pipe 31 to the inner surface of the first small-diameter pipe 31 up to the boundary portion with the first tapered pipe 33.

  On the other hand, as shown in FIG. 6, the hollow tube 30 has a second small-diameter tube 35 connected to the other end of the large-diameter tube 32, and an outer peripheral surface of the second small-diameter tube 35. A second serration 36 to which a steering handle (not shown) of the automobile is coupled may be formed and used in the steering apparatus of the automobile.

  Such a hollow tube 30 not only transmits the rotational force of the steering handle to a counterpart shaft (not shown) coupled to the first small-diameter tube 31, but also causes the counterpart shaft to move in the middle during a vehicle collision. It enters into the empty tube 30 side so that an impact can be absorbed.

  Here, the first serration 34 is provided to reach the boundary portion between the first small-diameter pipe 31 and the first tapered pipe 33, so that the mating shaft smoothly enters and is molded on the outer peripheral surface of the mating shaft. This prevents damage to the serration and damage to the first small-diameter pipe 31 of the hollow pipe, and smoothly absorbs the impact.

  An apparatus for forming the hollow tube 30 as described above is configured as follows.

  Referring to FIGS. 4 a to 4 d, this forming apparatus forms the hollow tube 30 so as to have a first small diameter tube 31, a large diameter tube 32 and a first taper tube 33, and the inner peripheral surface of the first small diameter tube 31. The first serration 34 is formed.

  This molding apparatus includes (1) a hollow die case 210 having an opening 211 formed at the upper end portion, and a slidably coupled to the die case 210, and a first taper portion 281 is formed at a central portion, A hollow first die 280 against which the empty tube 30 is pressed, and (2) a serration portion 221 is provided in the die case 210 in the length direction thereof, and an outer peripheral surface of the tip portion thereof. A core 220 to be pushed into, (3) a pressurizing means for pressurizing the hollow tube 30 so as to enter the first die 280 and the core 220, and (4) from the core 220 and the first die 280. And ejecting means for separating the hollow tube 30.

  The pressurizing means supplies a hydraulic medium to the inside of the die case 210 to generate hydraulic pressure, and discharges the hydraulic medium, and the hollow tube 30 and the first die coupled to the first die 280. A punch block 300 that pressurizes the die 280 toward the core 220; While the punch block 300 pressurizes the hollow tube 30 pushed into the first die 280 to form the first tapered tube in the hollow tube 30, the hydraulic pressure is applied by the pressurizing force of the punch block 300. Also, the hydraulic pressure is relatively smaller than the pressurizing force of the punch block 300 while the hollow tube 30 is coupled to the core 220 to form the first serration. .

  As the hydraulic means, as shown in FIG. 4d, a hydraulic pump 270 and an accumulator 260 that generate normal hydraulic pressure are employed.

  The ejecting means includes a first stripper 230 formed in a hollow shape and slidably coupled to the core 220, and an eject pin 240 that pushes the first stripper 230 in a direction in which the hollow tube 30 is detached. Prepare.

  With such a molding apparatus, as shown in FIG. 4 a, the hollow tube 30 to be molded is coupled to the die 280. At this time, the hydraulic medium is supplied from the hydraulic pump 270 into the die case 210, and the hydraulic pressure in the piston 250 is maintained while the punch block 300 pressurizes the hollow tube 30 as shown in FIG. Thus, the punch tube 300 is pressed so that the hollow tube 30 has the tapered tube 33 in the die 280.

  Next, as shown in FIG. 4 c, while the punch block 300 and the die 280 are further lowered to discharge the hydraulic medium, the hollow tube 30 is pushed into the gap between the core 220 and the inside of the first small diameter tube 31. A first serration 34 is formed on the peripheral surface. At this time, the first serration 34 is formed up to the boundary with the taper tube 33. After the first serration 34 is formed on the inner peripheral surface of the first small-diameter pipe 31, as shown in FIG. 4d, the hollow pipe 30 is discharged by the stripper 230 that rises by operating the eject pin 240. .

  In the hollow tube 30 formed by the above forming apparatus, the first serration 34 is formed up to the boundary with the taper tube 33, so that the mating shaft smoothly enters the first small diameter tube 31. become. In addition, damage to the inner peripheral surface of the first small-diameter pipe 31 and the serration portion of the counterpart shaft is prevented, and the impact is smoothly absorbed.

  On the other hand, when the first serration 34 is molded by the molding apparatus, elastic deformation occurs at the boundary with the taper tube 33, and the first serration 34 has a boundary between the taper tube 33 as shown in FIG. Serration 34a that is distorted at the portion is generated. For this reason, the entry of the mating shaft coupled to the first small diameter tube 31 is not smoothly performed, and the rigidity of the hollow tube 30 is reduced. Therefore, the molding accuracy of the first serration 34 is improved by processing the primary molded hollow tube with a finish molding apparatus as shown in FIGS. 5a to 5c.

  The finish forming apparatus includes: (1) a second tapered portion 410 having a diameter relatively smaller than that of the first tapered portion 281 of the first die 280 is formed, and the hollow tube 30 into which the molded hollow tube 30 is pushed is formed. A second die 400; (2) a punch block 300 that presses and presses the hollow tube 30 into the second die 400; and (3) a tip outer peripheral surface provided inside the second die 400 so as to be movable up and down. And (4) a second stripper 430 slidably coupled to the mandrel 420, and (5) interlocked with the second stripper 430. An eject pin 440 for ejecting the hollow tube 30 from the mandrel 420; and (6) an elastic bar in the eject direction of the hollow tube 30 for the mandrel 420. It comprises elastic means (spring) 450 to Ass.

  As shown in FIG. 5 a, the hollow tube 30 that has been primarily molded is inserted into the second die 400. And as FIG. 5 b shows, while pressurizing with the punch block 300, while the 1st small diameter pipe | tube 31 is pushed in in the 2nd taper part 410 relatively smaller than the 1st small diameter pipe | tube 31, The mandrel 420 enters the inside of the first small diameter pipe 31. At this time, the outer diameter of the first small-diameter pipe 31 is narrowed by the second taper portion 410, and as shown in FIG. 7, the outer diameter 30b of the hollow tube that has been secondarily formed is primarily formed. As compared with the outer diameter 30a of the hollow tube, it is biased toward the inside of the hollow tube 30. The mandrel 420 also narrows the inner diameter of the hollow tube that is secondarily formed. Thus, as shown in FIG. 7, the first serration 34b re-formed by the secondary forming and the first serration 34a formed by the primary forming and distorted are on the same axial straight line. Or the reshaped first serration 34b is located inside the distorted first serration 34a. In this way, the mating shaft assembled in the first small-diameter pipe 31 enters smoothly. Next, as shown in FIG. 5 c, the eject pin 440 is operated and the reshaped hollow tube 30 is discharged by the stripper 430.

  On the other hand, the method for forming the hollow tube as described above is as follows. This will be described with reference to FIGS. 4a to 5c. (1) A hollow tube 30 having a shape corresponding to the first die 280 is formed by pressing the hollow tube 30 to be formed on the first die 280 formed with a desired small diameter portion, a large diameter portion, and a tapered portion. And (2) a primary serration forming step of forming a first serration on the inner surface of the first small diameter tube 31 of the hollow tube until reaching a boundary portion between the first small diameter tube 31 and the first taper tube 33. (3) The molded hollow tube is pushed into the second die 400 having a taper portion 410 that is relatively smaller than the taper portion 281 of the first die 280, and the mandrel 420 formed with serrations is inserted into the second die 400. A secondary forming step of discharging after being pushed into the tapered tube 33 of the hollow tube is included.

  In such a forming method, serrations are formed on the surface of the hollow tube 30 where the first small-diameter tube 31 is not provided until the boundary portion with the tapered tube 33 is reached, and the tapered tube 33 is formed at the primary forming step. The distorted serration 34a formed in the part and the serration 34b reshaped by the secondary molding are located on the same axial straight line, or the reshaped first serration 34b is distorted first. It is located inside the serration 34a so that the mating shaft can enter smoothly and the rigidity of the hollow tube 30 is improved.

  The present invention as described above has a structure in which a rotational force is transmitted through a hollow tube to a mating shaft coupled to the first small-diameter tube, and at the same time the shock is absorbed while the mating shaft is pushed into the hollow tube. For example, in the event of a vehicle collision, the other party's shaft is pushed into the hollow tube, preventing the steering handle from projecting to the driver's side, and the rotational force of the steering handle is transmitted to the other party's shaft during normal times. Thus, the present invention can be employed in a steering apparatus for an automobile that allows the direction of the wheel to be controlled.

It is a schematic sectional drawing of the conventional steering shaft which employ | adopted the hollow tube. It is a schematic sectional drawing which shows the conventional hollow tube. It is the schematic (1) which shows the molding state of the hollow tube of this invention. It is the schematic (2) which shows the shaping | molding state of the hollow tube of this invention. It is the schematic (3) which shows the shaping | molding state of the hollow tube of this invention. It is an operation | movement figure (1) of the serration shaping | molding apparatus inside the hollow tube of this invention. It is an operation | movement figure (2) of the serration shaping | molding apparatus inside the hollow tube of this invention. It is an operation | movement figure (3) of the serration shaping | molding apparatus inside the hollow tube of this invention. It is an operation | movement figure (4) of the serration shaping | molding apparatus inside the hollow tube of this invention. It is an operation | movement figure (1) of the finish shaping | molding apparatus of this invention. It is an operation | movement figure (2) of the finish shaping | molding apparatus of this invention. It is an operation | movement figure (3) of the finish shaping | molding apparatus of this invention. It is sectional drawing of the state by which the hollow tube of this invention was employ | adopted for the steering shaft of the motor vehicle. It is a schematic sectional drawing which shows the state which the serration and the taper pipe part were distorted, and the state re-molded by the finish shaping | molding apparatus of this invention.

Explanation of symbols

30: Hollow tube 31: First small diameter tube 32: Large diameter tube 33: Tapered tube
34: 1st serration 210: Die case 220: Core 230: Stripper
240: Eject pin 280: Die 281: First taper

Claims (6)

In a serration molding device that molds serrations inside a hollow tube,
A hollow die case 210 having an opening at the upper end;
A hollow first die 280 that is slidably assembled to the die case 210, a first taper portion 281 is formed at a central portion, and the hollow tube 30 is pushed in;
The die case 210 is provided in the length direction thereof, and a serration portion 221 is formed on the outer peripheral surface of the tip portion thereof. The first serration is formed inside the hollow tube by being pushed into the hollow tube 30. A core 220;
Pressurizing means for pressurizing the hollow tube 30 against the first die 280 and the core 220;
A serration forming apparatus inside a hollow tube, comprising: ejecting means for separating the hollow tube 30 from the core 220 and the first die 280. The pressurizing means supplies hydraulic medium to the inside of the die case 210 to generate hydraulic pressure, and discharges the hydraulic medium, the hollow tube 30 assembled to the first die 280, and the A punch block 300 that pressurizes the first die 280 toward the core 220;
While the punch block 300 pressurizes the hollow tube 30 pushed into the first die 280 to form the first tapered tube in the hollow tube 30, the hydraulic pressure is higher than the applied pressure of the punch block 300. To be relatively large,
The hydraulic pressure is set to be relatively smaller than the applied pressure of the punch block (300) while the hollow tube (30) is assembled to the core (220) to form the first serration. The serration forming apparatus inside a hollow tube as described in 1.   The ejecting means includes a first stripper 230 that is formed in a hollow shape and is slidably combined with the core, and an eject pin 240 that pushes the first stripper 230 in a direction in which the hollow tube 30 is detached. The serration forming device inside a hollow tube according to claim 1 or 2, further comprising: The serration molding device inside the hollow tube is:
A hollow second die 400 into which the hollow tube 30 formed with the first serration is pushed,
A punch block 300 that presses and presses the hollow tube 30 into the second die 400;
A mandrel 420 provided inside the second die 400 so as to be movable up and down, serrated on the outer peripheral surface of the tip, and pushed into the hollow tube 30;
A second stripper 430 slidably combined with the mandrel 420;
An eject pin 440 for ejecting the hollow tube 30 from the mandrel 420 in conjunction with the second stripper 430;
The serration forming device inside a hollow tube according to claim 1, further comprising elastic means for elastically biasing the mandrel 420 in an ejecting direction of the hollow tube 30.   5. The hollow according to claim 4, wherein a second tapered portion 410 having a smaller diameter than the first tapered portion 281 of the first die 280 is formed in the second die 400. Serration molding device inside the tube. In the serration molding method for molding serrations inside the hollow tube,
A step of forming a hollow tube having a shape corresponding to the first die by pushing the hollow tube to be molded into the first die formed with a desired small diameter portion, a large diameter portion and a tapered portion;
A primary serration molding step of molding a first serration on the inner surface of the first small-diameter pipe 31 of the hollow pipe up to a boundary portion with the first tapered pipe 33;
The hollow tube formed with the first serration is pushed into a second die having a tapered portion whose inner diameter is smaller than the tapered portion of the first die, and the mandrel formed with the serration is used as the tapered tube of the hollow tube. A hollow tube forming method comprising: a secondary forming step in which the tube is discharged after being pushed into the tube.

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