JP7277706B2 - Method for manufacturing tube with different thickness and apparatus for manufacturing tube with different thickness - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a tube with different thicknesses and an apparatus for manufacturing a tube with different thicknesses.

BACKGROUND ART As a member constituting a vehicle body of an automobile, a member is used that has a portion that absorbs collision energy received in a collision or the like by collapsing itself and a portion that protects the vehicle body without collapsing. As one of such members, there is a tube having a different thickness along its length.

An example of a method for manufacturing a tube with a different thickness is disclosed in Patent Document 1.
FIG. 1 of Patent Literature 1 discloses a method for manufacturing a tube having a different thickness, which includes a locking step and an ironing step. In the locking step, the blank tube is placed in a die, and a plug is pushed in from one end side of the blank tube to expand the outer shape of the one end side while restricting movement in the longitudinal direction of the blank tube. to engage with the die. In the subsequent ironing process, while releasing the regulation of the blank pipe, the plug is pushed further toward the other end side of the blank pipe while maintaining the engagement of the blank pipe, thereby removing the blank. A thin-walled portion is formed by applying an ironing process to widen the inner shape while maintaining the outer shape of the pipe.
According to the manufacturing method described in Patent Literature 1, it is possible to easily manufacture a tube having a different thickness.

Japanese Patent No. 6256668

On the other hand, in order to widely apply different-thickness pipes to automobiles, it is required to be able to manufacture different-thickness pipes having a wide variety of shapes with a high yield. Therefore, there has been a demand for a manufacturing method that enables molding even with a high ironing rate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method for manufacturing a pipe with a different thickness, which enables manufacturing a pipe with a different thickness with a high yield even when the ironing rate is high. The challenge is to provide manufacturing equipment.

In order to solve the above problems and achieve the object, the present invention employs the following means. (1) A method for manufacturing a tube with different thickness according to one aspect of the present invention is a method for manufacturing a tube with different thickness from a hollow cylindrical base pipe having no flange , wherein the base pipe is placed in a die. a plug is pushed in from the one end of the blank tube while applying a reaction force to the other end against movement from the one end to the other end along the longitudinal direction of the blank tube, and It has an ironing process in which ironing is performed toward.
According to the method for manufacturing a pipe with a different thickness described in (1) above, since ironing is performed while supporting the blank pipe by applying a reaction force to the other end, the blank pipe can be diced even if the pressing force of the plug is increased. It can be fixed securely inside. Therefore, it is possible to prevent the blank tube from slipping in the die, so that the ironing rate can be increased.

(2) In the method for manufacturing a tube with different thicknesses described in (1) above, the die may be provided with an inclined surface facing the other end of the blank tube; In the working step, the plug is pushed in while receiving the other end of the blank tube on the inclined surface.
In the case of the method for manufacturing a pipe with a different thickness described in (2) above, when the plug is pushed into one end of the blank pipe and ironing is performed, elongation occurs toward the other end of the blank pipe. When the other end of the tube is extended while sliding on the inclined surface, it exerts a pressing force on the inclined surface. can always be maintained.

(3) In the method for manufacturing a tube with different thicknesses described in (2) above, the die may be provided with a parallel surface continuous with the inclined surface and along the longitudinal direction; When the plug is pushed in in the ironing process, the portion of the other end of the blank pipe that has passed through the inclined surface is further moved along the parallel surface.
In the case of the method for manufacturing a pipe with a different thickness described in (3) above, when the other end of the blank pipe extends while sliding on the inclined surface, the reaction force increases as the extension progresses. Then, of the other end portion of the blank tube, the portion that reaches the parallel surface through the inclined surface is not subjected to a high reaction force. Therefore, it is possible to prevent the reaction force acting on the other end of the blank tube from becoming too high unnecessarily.

(4) In the method of manufacturing a tube having a different thickness according to (2) or (3) above, the inclined surface may be formed within the die.
In the case of the method for manufacturing a pipe with a different thickness described in (4) above, since there is no need to use a separate jig, ironing can be performed using a simple method and apparatus.

(5) In the method of manufacturing a tube having a different thickness according to (2) or (3) above, the inclined surface may be formed on a first jig arranged in the die.
In the case of the method for manufacturing a pipe with a different thickness described in (5) above, the first jig is moved as the ironing progresses, or is replaced with another first jig having a different shape of the inclined surface. As a result, flexible ironing can be performed according to the desired product shape.

(6) In the method for manufacturing a pipe with a different thickness according to any one of (1) to (5) above, in the ironing step, the reaction force is divided into a plurality of positions along the longitudinal direction and the element It may be applied to said other end of the tube.
In the case of the method for manufacturing a pipe with a different thickness described in (6) above, by applying the reaction force to a plurality of locations, the load per location of the reaction force applied to the blank pipe can be reduced, so the product yield is improved. can be further increased.

(7) In the method for manufacturing a tube having a different thickness according to (1) above, the die may include a second jig with which the other end of the blank tube abuts. in the ironing step, the plug is pushed in while the second jig is retracted along the longitudinal direction while the second jig receives the other end of the blank tube.
In the case of the method for manufacturing a pipe with a different thickness described in (7) above, the reaction force can be continuously applied to the other end of the blank pipe while absorbing the elongation of the other end of the blank pipe caused by ironing. .

(8) In the method for manufacturing a pipe with a different thickness according to (7) above, in the ironing step, the pressing force applied by the blank pipe to the second jig is measured, and the pressing force is within a predetermined range. The retreating motion of the second jig may be controlled so as to fit.
In the case of the method for manufacturing a pipe with a different thickness described in (8) above, ironing is performed while feedback-controlling the retraction operation (at least one of the retraction speed and retraction amount) of the second jig so that the pressing force is constant. can do

(9) In the method for manufacturing a tube with different thickness according to any one of (1) to (8) above, the following may be performed: A diameter-enlarged recess having a cross-sectional shape perpendicular to the longitudinal direction larger than the outer diameter of the one end of the blank pipe is formed at a position; The outer diameter of the is enlarged to be engaged with the enlarged diameter concave portion.
In the case of the method for manufacturing a tube having a different thickness as described in (9) above, it is possible to enlarge the diameter of one end of the blank tube by pushing the plug in, and engage it with the diameter-enlarged concave portion. In this case, since both the locking at the position of one end of the blank pipe and the application of reaction force at the other end can be performed on the blank pipe, ironing with a higher ironing rate can be performed.

(10) In the method for manufacturing a differential thickness pipe according to any one of (1) to (9) above, the thickness reduction rate of the thin portion of the differential thickness pipe after the ironing process is 10% to 90%. may be within the range of
In the case of the method for manufacturing a pipe with a different thickness described in (10) above, since a wide range of thinning rate is set, it is possible to flexibly respond to the required product rigidity.

(11) In the method for manufacturing a differential thickness pipe according to any one of (1) to (10) above, the raw pipe may be a seamless steel pipe.
In the case of the method for manufacturing a pipe with a different thickness described in (11) above, even a seamless steel pipe with an uneven wall thickness can be formed into a pipe with a different wall thickness.

(12) An apparatus for manufacturing a tube with a different thickness according to an aspect of the present invention is an apparatus for manufacturing a tube with a different thickness from a hollow cylindrical blank pipe having no flange , and a storage section in which the blank tube is accommodated. a plug to be inserted into and removed from one end of the blank pipe in the housing portion; and the one end along the longitudinal direction of the blank pipe to the other end of the blank pipe in the housing portion. and a reaction force imparting portion that imparts a reaction force against the movement from toward the other end portion.
According to the apparatus for manufacturing a pipe with a different thickness described in (12) above, first, the raw pipe is put into the accommodating portion, and then inserted until the other end hits the reaction force applying portion. Subsequently, while the other end of the blank pipe is kept in contact with the reaction force applying portion, the plug is pushed into the blank pipe from one end thereof. At this time, the axial force applied to the blank tube by the plug is received by the reaction force applying portion and generates a reaction force, so that the blank pipe does not slip in the accommodating portion and is maintained fixed. Then, as the plug is pushed in, the inside of the blank tube is expanded and ironed. In this way, since ironing is performed while applying a reaction force to the other end of the blank pipe and supporting it, the blank pipe can be reliably fixed in the die even if the pressing force of the plug is increased. Therefore, it is possible to prevent the blank tube from slipping in the die, so that ironing can be performed with a high ironing rate.

(13) In the case of the apparatus for manufacturing a tube with different thicknesses described in (12) above, the reaction force applying portion may be an inclined surface facing the other end portion of the blank tube.
In the case of the apparatus for manufacturing a pipe with a different thickness described in (13) above, when the plug is pushed into one end of the blank pipe and the ironing process proceeds, elongation occurs toward the other end of the blank pipe. When the other end of the tube is extended while sliding on the inclined surface, it exerts a pressing force on the inclined surface. can always be maintained.

(14) In the case of the apparatus for manufacturing a pipe with a different thickness as described in (13) above, the reaction force application section may further have a parallel surface that is continuous with the inclined surface and extends along the longitudinal direction.
In the case of the apparatus for manufacturing a tube having a different thickness as described in (14) above, when the other end of the blank tube extends while being in sliding contact with the inclined surface, the reaction force increases as the extension progresses. Then, of the other end portion of the blank tube, the portion that reaches the parallel surface through the inclined surface is not subjected to a high reaction force. Therefore, it is possible to prevent the reaction force acting on the other end of the blank tube from becoming too high unnecessarily.

(15) In the case of the apparatus for manufacturing a tube with different thicknesses described in (13) or (14) above, the inclined surface may be formed within the die.
In the case of the apparatus for manufacturing a tube with different thickness described in (15) above, since it is not necessary to use a separate jig, the apparatus can be configured simply.

(16) In the case of the apparatus for manufacturing a tube with different thicknesses described in (13) or (14) above, the following may be provided: a first jig disposed within the die; is formed on the first jig.
In the case of the apparatus for manufacturing a pipe with a different thickness described in (16) above, the first jig is moved as the ironing progresses, or is replaced with another first jig having a different shape of the inclined surface. As a result, flexible ironing can be performed according to the desired product shape.

(17) In the case of the apparatus for manufacturing a pipe with a different thickness according to any one of (12) to (16) above, the reaction force applying section is arranged at a plurality of positions along the longitudinal direction. good too.
In the case of the apparatus for manufacturing a tube with different thicknesses described in (17) above, by applying the reaction force at a plurality of locations, the load per location of the reaction force applied to the blank pipe can be reduced, so the product yield is improved. can be further increased.

(18) In the case of the apparatus for manufacturing a tube with different thicknesses described in (12) above, the reaction force applying section is arranged in the die, faces the other end of the blank tube, and extends along the longitudinal direction. and a biasing portion that applies the reaction force to the second jig.
In the case of the apparatus for manufacturing a pipe with a different thickness according to the above (18), the elongation of the other end of the blank pipe caused by the ironing process is absorbed by the movement of the second jig, and the urging portion moves the blank pipe. It can continue to support while giving a reaction force to the other end.

(19) In the case of the apparatus for manufacturing a pipe with a different thickness according to (18) above, the reaction force application unit includes a measurement unit that measures the pressing force applied by the blank pipe to the second jig, and the measurement unit. and a control unit that controls the reaction force of the biasing unit so that the pressing force obtained by the above is within a predetermined range.
In the case of the apparatus for manufacturing a pipe with a different thickness described in (19) above, the controller causes the second jig to retract (at least the retraction speed and the retraction amount are On the other hand, ironing can be performed while feedback-controlling.

(20) In the case of the apparatus for manufacturing a tube with different thickness according to any one of (12) to (19) above, a A diameter-enlarged recess having a cross-sectional shape perpendicular to the outer diameter larger than the outer diameter of the one end of the base pipe may be formed.
In the case of the apparatus for manufacturing a tube having a different thickness as described in (20) above, it is possible to enlarge the diameter of one end of the blank tube by pushing the plug in, and engage it with the diameter-enlarging recess. In this case, since both the locking at the position of one end of the blank pipe and the application of reaction force at the other end can be performed on the blank pipe, ironing with a higher ironing rate can be performed.

According to each of the above aspects of the present invention, it is possible to perform appropriate ironing while preventing the blank pipe from slipping in the die. Therefore, even if the ironing rate is high, it is possible to manufacture pipes with different thicknesses at a high yield. .

FIG. 2 is a view for explaining each step of the manufacturing method of the differential thickness pipe according to the first embodiment of the present invention in the order of (a) to (b), showing a cross section including the axis of the differential thickness pipe manufacturing apparatus; It is a sectional view. It is a figure which shows the modification of the said 1st Embodiment, Comprising: It is sectional drawing which looked at the manufacturing apparatus of the differential thickness pipe|tube in the cross section containing the axis line. FIG. 10 is a view for explaining each step of the manufacturing method of the differential thickness pipe according to the second embodiment of the present invention in the order of (a) to (c), showing a cross section including the axis of the differential thickness pipe manufacturing apparatus; It is a sectional view. FIG. 10 is a view for explaining each step of the manufacturing method of the differential thickness pipe according to the third embodiment of the present invention in the order of (a) to (b), showing a cross section including the axis of the differential thickness pipe manufacturing apparatus; It is a sectional view. FIG. 10 is a view for explaining each step of the manufacturing method of the differential thickness pipe according to the fourth embodiment of the present invention in the order of (a) to (c), showing a cross section including the axis of the differential thickness pipe manufacturing apparatus; It is a sectional view. FIG. 11 is a view for explaining each step of the manufacturing method of the differential thickness pipe according to the fifth embodiment of the present invention in the order of (a) to (b), showing the differential thickness pipe manufacturing apparatus as viewed in cross section including its axis; It is a sectional view. It is a figure which shows the modification of the same 5th Embodiment, Comprising: It is sectional drawing which looked at the manufacturing apparatus of the differential thickness pipe|tube in the cross section containing the axis line. FIG. 10 is a view for explaining each step of the manufacturing method of the differential thickness pipe according to the sixth embodiment of the present invention in the order of (a) to (c), showing a cross section including the axis of the differential thickness pipe manufacturing apparatus; It is a sectional view. It is a figure which shows the modification of each embodiment of this invention, Comprising: It is a figure corresponded to the X section of FIG. (a) shows the case where the inclined surface is a concave surface, and (b) shows the case where the inclined surface is a convex surface.

Each embodiment of the present invention will be described below with reference to the drawings.
In each embodiment, a hollow cylindrical blank W is fixed in a die, and drawing is performed by pushing a plug from one end Wa of the blank tube W toward the other end Wb. In the description of each embodiment below, the direction toward one end Wa of the raw tube W may be called the front side, and the direction toward the other end Wb of the raw tube W may be called the back side.

As the blank tube W in each embodiment, one having a tensile strength of 290 MPa or more is preferably used. For example, as the base pipe W, one having a tensile strength of 440 MPa or 980 MPa can be used. In addition to steel, other metal materials such as aluminum can also be used as the material of the blank tube W. The base pipe W can be exemplified by a hollow cylindrical metal pipe (including a steel pipe), and a round steel pipe is particularly preferable. Any of seamless steel pipes, UO pipes, spiral pipes, and electric resistance welded steel pipes can be applied as round steel pipes.

[First embodiment]
FIG. 1 is a diagram for explaining each step of the method for manufacturing a tube with different thickness according to the first embodiment of the present invention in the order of (a) to (b), and includes the axis of the apparatus for manufacturing a tube with different thickness. It is sectional drawing seen in the cross section.
First, an apparatus for manufacturing a tube with different thickness according to the present embodiment (hereinafter referred to as "ironing apparatus") will be described.
The ironing apparatus of the present embodiment is an apparatus for manufacturing a tube P having a different thickness from a blank tube W having a hollow cylindrical shape. As shown in FIG. 1( a ), the ironing device includes a die 10 , a plug 20 , a plug driving device (not shown), and a reaction force applying section 30 .

The die 10 includes a housing portion 11, a tapered portion 12, and a small diameter portion 13, and is fixedly arranged at a fixed position.
The housing portion 11 is a cylindrical space corresponding to the outer diameter of the raw pipe W, and houses the raw pipe W. As shown in FIG. The accommodating portion 11 has an inner diameter dimension substantially the same as the outer diameter dimension of the base pipe W. As shown in FIG. The length dimension of the accommodation portion 11 along the axis CL is longer than or the same as the length dimension of the blank tube W. As shown in FIG. One end side of the housing portion 11 is an insertion port 11a for the raw pipe W, and the other end side of the housing portion 11 is an insertion end 11b where the other end portion Wb of the raw pipe W is fixed before processing.

The tapered portion 12 is a truncated cone-shaped space that continues to the insertion end 11b of the housing portion 11 and has a diameter that decreases along the axis CL as it moves away from the insertion end 11b. The tapered portion 12 has a tapered inlet 12a having the same inner diameter as the insertion end 11b and a tapered outlet 12b having a smaller inner diameter than the tapered inlet 12a. Between the tapered entrance 12a and the tapered exit 12b is a linear inclined surface in a cross section including the axis line CL. Since the inner diameter of the tapered portion 12 is smaller than the outer diameter of the raw pipe W, the raw pipe W is not inserted into the tapered portion 12 before processing. Therefore, the end face position of the other end portion Wb of the blank pipe W inserted into the housing portion 11 coincides with the position of the insertion end 11b, and is temporarily fixed at this position.
The small-diameter portion 13 is a columnar space that continues to the tapered outlet 12b of the tapered portion 12 and has a constant inner diameter along the axis CL. The small diameter portion 13 has an inlet 13a and an outlet 13b having the same inner diameter as the tapered outlet 12b.
The accommodating portion 11, the tapered portion 12, and the small-diameter portion 13 are coaxially arranged in a row so as to share the axis CL.

The plug 20 includes a base portion 21 and a tip portion 22, and is a component that is inserted into and removed from the one end portion Wa of the blank tube W. As shown in FIG.
The base 21 has a cylindrical shape with a constant outer diameter at each position along the axis CL. The outer diameter dimension of the base portion 21 is larger than the inner diameter dimension of the base pipe W and smaller than the outer diameter dimension of the base pipe W. The outer diameter dimension of the base portion 21 is determined according to the ironing rate when ironing the blank pipe W. As shown in FIG.
The distal end portion 22 continues to the base portion 21 and has a truncated cone shape whose diameter decreases along the axis CL as it moves away from the proximal end position 22a. The outer diameter dimension of the tip portion 22 is the same as the outer diameter dimension of the base portion 21 at its base end position 22a, and is larger than the inner diameter dimension of the blank tube W. As shown in FIG. The outer diameter dimension of the tip portion 22 is smaller than the outer diameter dimension at the base end position 22a at the tip position 22b and smaller than the inner diameter dimension of the blank tube W at the tip position 22b. Between the distal end position 22b and the proximal end position 22a, a linear inclined surface is formed in a cross section including the axis line CL. The shape of the distal end portion 22 at the base end position 22a is circular when viewed from the opposite side along the axis CL. The shape of the tip portion 22 at the tip position 22b is also circular when viewed from the opposite side along the axis CL.
The plug driving device is a hydraulic cylinder to which the base 21 of the plug 20 is coaxially fixed, and moves the plug 20 forward and backward along the axis CL. The forward/backward stroke of the plug 20 by the plug driving device is determined according to the length of the thin portion formed in the blank W by ironing.

The reaction force applying portion 30 is formed by combining the inner peripheral surface 12 x of the tapered portion 12 and the inner peripheral surface 13 x of the small diameter portion 13 . The inner peripheral surface 12x is an inclined surface facing the other end portion Wb of the blank tube W when viewed along the axis CL, and is formed inside the die 10 . The inner peripheral surface 13x is a parallel surface continuous with the inner peripheral surface 12x and parallel to the direction of the axis CL. Thus, the reaction force applying portion 30 is formed in the die 10 as a combination of the inner peripheral surface 12x and the inner peripheral surface 13x. The reaction force applying portion 30 is tapered at its inner peripheral surface 12x. Therefore, when the plug 20 presses the one end Wa of the raw tube W placed in the housing portion 11, the inner peripheral surface 12x extends along the longitudinal direction of the raw tube W with respect to the other end Wb. to the other end Wb. Since this reaction force is obtained as a reaction against the pressing force of the plug 20, the larger the pressing force, the larger the reaction force.

A method for manufacturing a pipe having a different thickness using the ironing apparatus having the above-described configuration will be described below. As shown in FIGS. 1(a) and 1(b), the method for manufacturing a tube with different thickness according to the present embodiment is a method for manufacturing a tube with different thickness P from a hollow cylindrical base tube W, and includes an ironing process. have
In this ironing process, first, as shown in FIG. At this time, the end face position of the other end portion Wb of the blank pipe W is fixed at the position of the insertion end 11b. However, at this time point, no reaction force is applied to the end face of the blank tube W yet. The end face position of the one end Wa of the blank tube W is the same as the insertion opening 11a of the housing portion 11, or is located on the back side of the insertion opening 11a. Further, the base tube W is arranged coaxially with the accommodating portion 11 so as to share the axis line CL.

After placing the tube W, as shown in FIG. 1(b), the plug 20 is inserted from one end Wa of the tube W, and the plug 20 is further pushed toward the other end Wb for ironing. This ironing process is performed while applying a reaction force to the other end portion Wb of the raw pipe W against the movement of the raw pipe W along the longitudinal direction from the one end portion Wa toward the other end portion Wb. In this way, since ironing is performed while supporting the blank tube W by applying a reaction force to the other end Wb, the blank tube W can be reliably fixed in the die 10 even if the force for pushing the plug 20 is increased. Therefore, the raw tube W can be prevented from slipping in the die 10, and the ironing rate can be increased.

When the plug 20 is pushed into the raw tube W with the raw tube W fixed in this way, the inner diameter of the raw tube W is expanded by the plug 20, and the outer diameter dimension of the base 21 of the plug 20 is almost the same as that of the base 21 of the plug 20. be the same. A portion of the blank tube W whose inner diameter is expanded becomes a thin-walled portion P1 that is thinner than the state before processing.
As the wall thickness is reduced by ironing, the other end portion Wb of the blank tube W is extended and pushed out from the accommodating portion 11 to the tapered portion 12 and then to the small diameter portion 13 . That is, first, the thickness of the other end portion Wb of the blank pipe W is restrained by the inclined surface (inner peripheral surface) of the tapered portion 12 and is gradually narrowed down. At this time, the other end portion Wb of the blank pipe W extends while slidingly contacting the inclined surface of the taper portion 12, and thus exerts a pressing force on the inclined surface. Since this pressing force is returned to the blank tube W itself as a reaction force due to reaction, the fixed state of the blank tube W can always be maintained. Therefore, the thin portion P1 can be formed without the position of the one end portion Wa of the blank tube W being largely displaced.

The other end Wb, which has passed the position of the taper portion 12 by pushing the plug 20, further extends to reach the inside of the small diameter portion 13 from the inlet 13a. The other end portion Wb in the small diameter portion 13 moves along the parallel surface (inner peripheral surface) of the small diameter portion 13, and stops expanding when the plug 20 stops being pushed. Since the end face of the other end Wb stops at a position on the front side of the outlet 13 b of the small diameter portion 13 , it does not protrude outside the die 10 .
When the other end portion Wb of the blank pipe W extends while sliding on the inclined surface of the tapered portion 12, the reaction force also increases along with the extension. The portion reaching the parallel surface of the portion 13 does not receive a high reaction force. Therefore, it is possible to prevent the reaction force acting on the other end portion Wb of the blank tube W from becoming too high unnecessarily.

Through the steps described above, a tube P having a different thickness described below can be formed from the blank tube W.
The differential-thickness pipe P has a hollow cylindrical shape having one end Wa and the other end Wb, and has a thin portion P1 thinner than the other end Wb. The other end portion Wb has a narrowed portion P2 having a smaller outer diameter than other portions along the longitudinal direction. A thick portion P3 is provided between the thin portion P1 and the constricted portion P2. Since the thick portion P3 has the same outer diameter as the thin portion P1 and a smaller inner diameter than the thin portion P1, the thick portion P3 is thicker than the thin portion P1. The thick portion P3 has an outer diameter dimension and an inner diameter dimension larger than those of the aperture portion P2. The thick portion P3 has the same outer diameter as the raw pipe W and an inner diameter that is substantially the same as or slightly smaller than that of the raw pipe W. The differential thickness pipe P has a longer overall length than the raw pipe W before processing.
The differential-thickness pipe P of the present embodiment may be further processed to have a product shape with a rounded end portion. In this embodiment, since the tip is narrowed in advance by the tapering portion P2, post-processing for rounding can be easily performed.

The thickness reduction rate of the thin portion P1 of the pipe with different thickness P after the ironing process is within the range of 10% to 90%. In order to improve the strength of the thin portion P1 by ironing, the rate of reduction in wall thickness of the blank pipe W by ironing must be 10% or more. On the other hand, if the wall thickness reduction rate of the blank tube W due to ironing exceeds 90%, there is a risk of breakage, seizure, or the like. Therefore, the thickness reduction rate when ironing the blank pipe W is preferably within the range of 10 to 90%. Preferably, the thickness reduction rate is within the range of 20 to 80%. Note that the thickness reduction rate (%) is defined as ( _{d 0} −d)/d ₀ ×100 (%).

Here, when the wall thickness d of the thin wall portion P1 after the ironing process is not uniform when viewed along the longitudinal direction of the blank pipe W, but has a distribution, the numerical value obtained at the point where the amount of wall thinning is the largest is Adopted as a reduction rate. That is, the value obtained at the portion where the difference (equivalent strain amount) obtained by subtracting d from _d0 when viewed along the longitudinal direction of the thin portion P1 is the largest is adopted as the aforementioned thickness reduction rate. . Further, when the thickness reduction amount is not uniform but distributed along the circumferential direction of the blank pipe W, the value obtained at the location where the thickness reduction amount is the largest in the circumferential distribution is used as the thickness reduction described above. adopted as a rate.
The thickness reduction rate can be adjusted by adjusting the outer diameter of the base portion 21 of the plug 20 . The above-described appropriate range for the thickness reduction rate is the same for other embodiments described later.

As described above, the method of manufacturing a tube with different thickness according to the present embodiment is a method of manufacturing a tube with different thickness P from a hollow tubular blank W, and inserting the blank W into the die 10. , and while applying a reaction force to the other end Wb against the movement of the raw pipe W from the one end Wa toward the other end Wb along the longitudinal direction, the plug 20 is pushed from the one end Wa of the raw pipe W. There is an ironing step of pressing and ironing toward the other end portion Wb.
According to this method of manufacturing a tube with a different thickness, ironing is performed while applying a reaction force to the other end Wb to support the blank tube W. can be fixed securely. Therefore, since the blank pipe W can be prevented from slipping in the die 10, even if the ironing rate is high, the differential thickness pipe P can be manufactured with a high yield.

In the above-described first embodiment, the reaction force is applied to the blank tube W only at one point of the tapered portion 12. However, the present invention is not limited to this configuration. It may be applied to the other end Wb of W. This modification will be described with reference to FIG. FIG. 2 is a diagram showing a modification of the first embodiment, and is a cross-sectional view including the axis line of the pipe P having a different thickness.
In this modified example, a die 10A is used in which the tapered portion 12 is divided into two portions (a first tapered portion 12A and a second tapered portion 12B) along the axis CL. In the ironing process, the plug 20 is pushed in from the one end Wa of the blank tube W placed in the housing portion 11, as in the first embodiment. Then, the blank tube W is ironed, and the other end portion Wb is elongated while receiving a reaction force from the first tapered portion 12A. As the plug 20 is further pushed in, the blank tube W extends while receiving the reaction force from the second taper portion 12B in addition to the reaction force from the first taper portion 12A. Then, the pressing of the plug 20 is stopped and the plug 20 is pulled out, thereby completing the forming of the pipe P having a different thickness.

The formed differential thickness pipe P is narrowed at two locations in its longitudinal direction, and a thin portion P1 is formed at one end Wa. By applying the reaction force at two locations in this manner, the load per location of the reaction force applied to the blank tube W can be reduced, so that it is possible to further increase the yield.

[Second embodiment]
3A to 3C are diagrams for explaining each step of the manufacturing method of the differential thickness pipe according to the second embodiment of the present invention in the order of (a) to (c). FIG. 3 is a cross-sectional view as viewed in an inclusive cross-section; Hereinafter, the description will be made based on FIG. 3, but mainly the differences from the first embodiment will be described, and the same components as those of the first embodiment will be denoted by the same reference numerals. omitted.

As shown in FIG. 3( a ), the apparatus for manufacturing a tube with different thickness according to the present embodiment (hereinafter referred to as “ironing apparatus”) is positioned at a position corresponding to one end Wa of the blank tube W in the housing portion 11 . , a diameter-enlarged concave portion 11x having a cross-sectional shape perpendicular to the longitudinal direction that is larger than the outer diameter of one end Wa of the base pipe W. As shown in FIG.
The enlarged diameter recess 11x has a parallel portion 11x1 and a tapered portion 11x2. The parallel portion 11x1 has an inner diameter dimension larger than the outer diameter dimension of the blank tube W, and is a space with a constant inner diameter dimension at each position along the axis CL. The tapered portion 11x2 is a space that continues to the parallel portion 11x1, and is tapered along the axis CL with increasing distance from the parallel portion 11x1. One end side of the tapered portion 111x2 is equal to the inner diameter dimension of the parallel portion 11x1, and the other end side is substantially equal to the outer diameter dimension of the blank tube W.

A method for manufacturing a pipe having a different thickness using the ironing apparatus having the above-described configuration will be described below.
In the ironing process of the present embodiment, first, as shown in FIG. 3(a), the blank tube W is arranged in the housing portion 11 of the die 10B. At this time, the end surface position of the other end portion Wb of the blank pipe W is temporarily fixed at the position of the insertion end 11b. However, at this point in time, the reaction force has not yet been applied to the other end Wb. The end surface position of the one end Wa of the blank tube W is the same as the insertion opening 11a of the housing portion 11, or is located on the back side of the insertion opening. Further, the base tube W is arranged coaxially with the accommodating portion 11 so as to share the axis line CL. Since the one end Wa of the blank tube W is positioned inside the expanded diameter recess 11x, an annular gap is formed around the one end Wa.
Before the plug 20 is pushed in in the next step, a dummy pipe (not shown) or the like is pressed against the end surface of the other end Wb of the blank tube W as indicated by the Δ mark in FIG. W may be temporarily fixed.

After placing the tube W, as shown in FIG. 3(b), the plug 20 is inserted from one end Wa of the tube W and pushed. Then, the plug 20 expands the inner and outer diameters of the one end Wa of the blank tube W. As shown in FIG. As a result, the one end Wa of the blank tube W is enlarged (diameter-enlarged) and fitted into the diameter-enlarged concave portion 11x without a gap, and locked.

Subsequently, as shown in FIG. 3(c), ironing is performed by further pushing the plug 20 toward the other end portion Wb. In this ironing process, as in the first embodiment, a reaction force is applied to the other end portion Wb of the raw pipe W to resist movement from the one end portion Wa toward the other end portion Wb along the longitudinal direction of the raw pipe W. It is done while In addition, in the present embodiment, the one end Wa of the blank tube W is engaged with the enlarged diameter concave portion 11x. Therefore, both locking at the position of the one end Wa of the blank tube W and application of reaction force at the position of the other end Wb can be performed.

When the plug 20 is pushed into the blank tube W in this state, the inner diameter of the blank tube W is expanded by the plug 20 and becomes substantially the same as the outer diameter dimension of the base portion 21 of the plug 20 . A portion of the raw tube W whose inner diameter is expanded while the outer diameter is constrained by the inner diameter of the housing portion 11 becomes a thin portion P1 having a thickness smaller than that before processing.
As the wall thickness is reduced by ironing, the other end portion Wb of the blank tube W is extended and pushed out from the accommodating portion 11 to the tapered portion 12 and then to the small diameter portion 13 . During this time, both the engagement at the position of the one end Wa of the blank pipe W and the application of the reaction force at the position of the other end Wb are continuously performed. Therefore, the thin portion P1 can be formed without the position of the one end portion Wa of the blank tube W being largely displaced.
The other end Wb that has passed through the tapered portion 12 by pushing the plug 20 further extends into the small diameter portion 13 . The other end portion Wb in the small diameter portion 13 moves along the parallel surface (inner peripheral surface) of the small diameter portion 13, and stops expanding when the plug 20 stops being pushed. Since the end surface of the other end portion Wb stops at a position within the small diameter portion 13, it does not protrude outside the die 10B.

Through the steps described above, a tube P having a different thickness described below can be formed from the blank tube W.
The differential thickness pipe P has a hollow cylindrical shape having one end Wa and the other end Wb, and has an enlarged diameter portion P4 having an enlarged inner diameter and an outer diameter at the one end Wa. Between the one end Wa and the other end Wb, there is a thin portion P1 thinner than the one end Wa and the other end Wb. The other end portion Wb has a narrowed portion P2 having a smaller outer diameter than other portions along the longitudinal direction. A thick portion P3 is provided between the thin portion P1 and the constricted portion P2. Since the thick portion P3 has the same outer diameter as the thin portion P1 and a smaller inner diameter than the thin portion P1, the thick portion P3 is thicker than the thin portion P1. The thick portion P3 has an outer diameter dimension and an inner diameter dimension larger than those of the aperture portion P2. The thick portion P3 has the same outer diameter as the raw pipe W and an inner diameter that is substantially the same as or slightly smaller than that of the raw pipe W. The differential thickness pipe P has a longer overall length than the raw pipe W before processing.

According to the manufacturing method of the differential-thickness tube according to the present embodiment described above, the same effects as those of the first embodiment can be obtained. In addition, according to the present embodiment, since the enlarged diameter portion P4 is formed and engaged with the enlarged diameter recessed portion 11x, pushing the plug 20 causes the one end portion Wa of the blank tube W to be enlarged in diameter to fit into the enlarged diameter recessed portion 11x. can be locked. In this case, since both the locking at the position of the one end Wa of the blank pipe W and the application of the reaction force at the other end Wb can be performed on the blank pipe W, ironing with a higher ironing rate can be performed.

[Third Embodiment]
FIG. 4 is a diagram for explaining each step of the manufacturing method of the differential thickness pipe according to the third embodiment of the present invention in the order of (a) to (b), and includes the axis of the differential thickness pipe manufacturing apparatus. It is sectional drawing seen in the cross section.
First, an apparatus for manufacturing a tube with different thickness according to the present embodiment (hereinafter referred to as "ironing apparatus") will be described.
The ironing apparatus of the present embodiment is an apparatus for manufacturing a tube P having a different thickness from a blank tube W having a hollow cylindrical shape. As shown in FIG. 4A, the ironing device includes a die 110, a plug 20, a plug driving device (not shown), a jig (first jig) 140, and a jig driving device (not shown). shown).

The die 110 includes a housing portion 111, a tapered portion 112, and a large diameter portion 113, and is fixedly arranged at a fixed position.
The accommodation portion 111 is a columnar space corresponding to the outer diameter of the blank tube W. As shown in FIG. The accommodating portion 111 has an inner diameter dimension that is approximately the same as the outer diameter dimension of the base pipe W. As shown in FIG. The length dimension of the accommodation portion 111 along the axis CL is longer than or the same as the length dimension of the blank tube W. As shown in FIG. One end side of the accommodating portion 111 is an insertion opening 111a for the blank tube W, and the other end side of the accommodating portion 111 is an insertion end 111b where the other end portion Wb of the blank tube W is fixed before processing.

The tapered portion 112 is a truncated cone-shaped space that continues to the insertion end 111b of the housing portion 111 and expands along the axis CL as the distance from the insertion end 111b increases. The tapered portion 112 has a tapered inlet 112a having the same inner diameter as the insertion end 111b and a tapered outlet 112b having a larger inner diameter than the tapered inlet 112a. Between the tapered entrance 112a and the tapered exit 112b is a linear inclined surface in a cross section including the axis line CL.
The large-diameter portion 113 is a cylindrical space that continues to the tapered outlet 112b of the tapered portion 112 and has a constant inner diameter along the axis CL. The large diameter portion 113 has an inlet 113a and an outlet 113b that have the same inner diameter as the tapered outlet 112b.
The accommodating portion 111, the tapered portion 112, and the large-diameter portion 113 are coaxially arranged in a row so as to share the axis CL.

Since the plug 20 and the plug driving device have the same configurations as those of the first embodiment, the same reference numerals are used and the description thereof is omitted.

The jig 140 shares the axis CL with the die 110 and is arranged so as to be freely inserted into and removed from the other end portion Wb of the blank tube W from the inner side of the die 110 . The jig 140 has a small diameter portion 141 , a base portion 142 and a tapered portion 143 .
The small-diameter portion 141 has a columnar shape, and its outer diameter is slightly smaller than the inner diameter of the raw pipe W. As shown in FIG. The base portion 142 has a columnar shape and an outer diameter dimension larger than that of the small diameter portion 141 . The tapered portion 143 is arranged between the small-diameter portion 141 and the base portion 142 and has a truncated cone shape that expands along the direction from the small-diameter portion 141 toward the base portion 142 . Since the outer diameter dimension of the tapered portion 143 is larger than the inner diameter dimension of the blank pipe W, the blank pipe W before processing is not inserted into the tapered portion 112 . Therefore, the end face position of the other end portion Wb of the blank pipe W inserted into the housing portion 111 coincides with the position of the insertion end 111b, and is fixed at this position.

The combination of the outer peripheral surface (inclined surface) 143a of the tapered portion 143 and the outer peripheral surface (parallel surface) 142a of the base portion 142 forms the reaction force applying portion 130 . The reaction force applying portion 130 widens at its tapered portion 143 . Therefore, when the plug 20 presses the one end Wa of the raw pipe W arranged in the housing portion 11, the outer peripheral surface 143a is pushed from the one end Wa along the longitudinal direction of the raw pipe W with respect to the other end Wb. A reaction force is applied to resist the movement toward the other end Wb. Since this reaction force is obtained as a reaction against the pressing force of the plug 20, the larger the pressing force, the larger the reaction force.
The jig driving device is a hydraulic cylinder to which the base 142 of the jig 140 is coaxially fixed, and moves the jig 140 forward and backward along the axis CL.

A method for manufacturing a pipe having a different thickness using the ironing apparatus having the above-described configuration will be described below. As shown in FIGS. 4(a) and 4(b), the method for manufacturing a differential thickness pipe according to the present embodiment is a method for producing a differential thickness pipe P from a hollow cylindrical base pipe W, and includes an ironing process. have
In this ironing process, first, as shown in FIG. At this time, the end face position of the other end portion Wb of the blank pipe W is fixed at the position of the insertion end 111b. However, at this point in time, the reaction force has not yet been applied to the other end Wb. The end face position of the one end Wa of the blank tube W is the same as the insertion opening 111a of the housing portion 111, or is located on the back side of the insertion opening 111a. Further, the base tube W is arranged coaxially with the accommodating portion 111, sharing the axis line CL.

After placing the tube W, as shown in FIG. 4(b), the plug 20 is inserted from one end Wa of the tube W, and the plug 20 is pushed toward the other end Wb for ironing. This ironing process is performed while applying a reaction force to the other end portion Wb of the raw pipe W against the movement of the raw pipe W along the longitudinal direction from the one end portion Wa toward the other end portion Wb. In this way, ironing is performed while applying a reaction force to the other end portion Wb to support the blank tube W, so that the blank tube W can be reliably fixed in the die 110 even if the pressing force of the plug 20 is increased. Therefore, the raw tube W can be prevented from slipping in the die 110, and the ironing rate can be increased.

When the plug 20 is pushed into the raw tube W with the raw tube W fixed in this way, the inner diameter of the raw tube W is expanded by the plug 20, and the outer diameter dimension of the base 21 of the plug 20 is almost the same as that of the base 21 of the plug 20. be the same. A portion of the blank tube W whose inner diameter is expanded becomes a thin-walled portion P1 that is thinner than the state before processing.
The other end portion Wb of the blank tube W is extended and pushed out from the accommodation portion 111 to the tapered portion 112 and then to the large diameter portion 113 as the wall thickness is reduced by the ironing. That is, first, the thickness of the other end portion Wb of the blank tube W is gradually increased by being urged by the outer peripheral surface (inclined surface) 143a of the tapered portion 143 to increase in diameter. At this time, the other end portion Wb of the base pipe W extends while being in sliding contact with the outer peripheral surface 143a of the tapered portion 143, and thus exerts a pressing force on the outer peripheral surface 143a. Since this pressing force is returned to the blank tube W itself as a reaction force due to reaction, the fixed state of the blank tube W can always be maintained. Therefore, the thin portion P1 can be formed without the position of the one end portion Wa of the blank tube W being largely displaced.

The other end Wb that has passed through the position of the tapered portion 143 due to the pushing of the plug 20 further extends to reach the outer circumference of the base portion 142 . The other end Wb that has reached the outer periphery of the base 142 moves along the parallel surface (outer peripheral surface) of the base 142 and stops expanding when the plug 20 stops being pushed. The end surface of the other end Wb does not protrude outside the die 110 .
When the other end portion Wb of the blank pipe W extends while sliding on the outer peripheral surface 143a of the tapered portion 143, the reaction force increases as the extension progresses. A portion reaching the outer peripheral surface 142a of the base portion 142 through the base portion 142 is not subjected to a high reaction force. Therefore, it is possible to prevent the reaction force acting on the other end portion Wb of the blank tube W from becoming too high unnecessarily.

Through the steps described above, a tube P having a different thickness described below can be formed from the blank tube W.
The differential-thickness pipe P has a hollow cylindrical shape having one end Wa and the other end Wb, and has a thin portion P1 thinner than the other end Wb. The other end portion Wb has a flared portion P5 having an inner diameter and an outer diameter larger than those of other portions along the longitudinal direction. A thick portion P3 is provided between the thin portion P1 and the flared portion P5. Since the thick portion P3 has the same outer diameter as the thin portion P1 and a smaller inner diameter than the thin portion P1, the thick portion P3 is thicker than the thin portion P1. The thick portion P3 has an outer diameter dimension and an inner diameter dimension smaller than those of the flared portion P5. The thick portion P3 has the same outer diameter as the raw pipe W and an inner diameter that is substantially the same as or slightly smaller than that of the raw pipe W. The differential thickness pipe P has a longer overall length than the raw pipe W before processing.

As described above, the method of manufacturing a tube with different thickness according to the present embodiment is a method of manufacturing a tube with different thickness P from a hollow tubular blank W, and inserting the blank W into the die 110. , and while applying a reaction force to the other end Wb against the movement of the raw pipe W from the one end Wa toward the other end Wb along the longitudinal direction, the plug 20 is pushed from the one end Wa of the raw pipe W. There is an ironing step of pressing and ironing toward the other end portion Wb.
According to this method of manufacturing a tube with a different thickness, ironing is performed while applying a reaction force to the other end Wb to support the blank tube W. can be fixed securely. Therefore, since the blank pipe W can be prevented from slipping in the die 110, even if the ironing rate is high, the differential thickness pipe P can be manufactured with a high yield.
Furthermore, in this embodiment, a jig 140 having an inclined surface that forms the reaction force applying portion 130 is employed. According to this configuration, by exchanging a plurality of jigs 140 having different shapes or by changing the way of movement of the jigs 140, flexible ironing can be performed in accordance with the desired product shape.

[Fourth Embodiment]
FIG. 5 is a diagram for explaining each step of the manufacturing method of the differential thickness pipe according to the fourth embodiment of the present invention in the order of (a) to (c), and includes the axis of the differential thickness pipe manufacturing apparatus. It is sectional drawing seen in the cross section. Hereinafter, the description will be made based on FIG. 5, but mainly the differences from the third embodiment will be described, and the same components as those of the third embodiment will be denoted by the same reference numerals. omitted.

As shown in FIG. 5( a ), the apparatus for manufacturing a tube with different thickness according to the present embodiment (hereinafter referred to as “ironing apparatus”) is positioned at a position corresponding to one end Wa of the blank tube W in the housing portion 111 . , a diameter-enlarging recess 111x having a cross-sectional shape orthogonal to the longitudinal direction that is larger than the outer diameter of one end Wa of the base pipe W. As shown in FIG.
The enlarged diameter recess 111x has a parallel portion 111x1 and a tapered portion 111x2. The parallel portion 111x1 has an inner diameter dimension larger than the outer diameter dimension of the blank tube W, and is a space with a constant inner diameter dimension at each position along the axis CL. The tapered portion 111x2 is a space that continues to the parallel portion 111x1, and is tapered along the axis CL with increasing distance from the parallel portion 111x1. One end side of the tapered portion 111x2 is equal to the inner diameter dimension of the parallel portion 111x1, and the other end side is substantially equal to the outer diameter dimension of the blank tube W.

A method for manufacturing a pipe having a different thickness using the ironing apparatus having the above-described configuration will be described below.
In the ironing process of the present embodiment, first, as shown in FIG. 5(a), the blank tube W is arranged in the housing portion 111 of the die 110A. The end face position of the one end Wa of the blank tube W is the same as the insertion opening 111a of the housing portion 111, or is located on the back side of the insertion opening 111a. Further, the base tube W is arranged coaxially with the accommodating portion 111, sharing the axis line CL. Since the one end Wa of the base pipe W is located inside the expanded diameter recess 111x, an annular gap is formed around the one end Wa.
Before the plug 20 is pushed in in the next step, a dummy pipe (not shown) or the like is pressed against the end face of the other end Wb of the blank tube W as indicated by the Δ mark in FIG. Temporarily fix W.

After placing the tube W, the plug 20 is inserted from one end Wa of the tube W as shown in FIG. 5(b). Then, the plug 20 expands the inner and outer diameters of the one end Wa of the blank tube W. As shown in FIG. As a result, the one end Wa of the blank tube W is expanded in diameter and fitted into the enlarged diameter concave portion 111x without any gap, and is locked. In this locked state, the push-in of the plug 20 is temporarily stopped. Subsequently, the dummy pipe is removed, and instead, the jig driving device is driven to place the jig 140 at the position shown in FIG. 5(c).

After the jig 140 is installed, the ironing process is performed by pushing the plug 20 again toward the other end Wb. In this ironing process, as in the third embodiment, a reaction force is applied to the other end portion Wb of the raw pipe W to resist movement from the one end portion Wa toward the other end portion Wb along the longitudinal direction of the raw pipe W. It is done while In addition, in the present embodiment, the one end Wa of the blank tube W is engaged with the enlarged diameter concave portion 111x. Therefore, both locking at the position of the one end Wa of the blank tube W and application of reaction force at the position of the other end Wb can be performed.

When the plug 20 is pushed into the blank tube W in this state, the inner diameter of the blank tube W is expanded by the plug 20 and becomes substantially the same as the outer diameter dimension of the base portion 21 of the plug 20 . A portion of the blank tube W whose inner diameter is expanded while the outer diameter is constrained by the inner diameter of the accommodating portion 111 becomes a thin portion P1 having a thickness smaller than that before processing.
The other end portion Wb of the blank tube W is extended and pushed out from the accommodation portion 111 to the tapered portion 112 and then to the large diameter portion 113 as the wall thickness is reduced by the ironing. During this time, both the engagement at the position of the one end Wa of the blank pipe W and the application of the reaction force at the position of the other end Wb are continuously performed. Therefore, the thin portion P1 can be formed without the position of the one end portion Wa of the blank tube W being largely displaced.
The other end Wb that has passed through the position of the tapered portion 143 by pushing the plug 20 further extends to reach the circumference of the base portion 142 . The other end portion Wb around the base portion 142 moves along the outer peripheral surface (parallel surface) 142a of the base portion 142, and stops expanding when the plug 20 stops being pushed. The end face of the other end Wb does not protrude outside the die 110A.
Then, the plug 20 and the jig 140 are pulled out from the blank tube W. After that, the die 110A is separated into two sections including the axis line CL to take out the tube P of different thickness.

Through the steps described above, a tube P having a different thickness described below can be formed from the blank tube W.
The differential thickness pipe P has a hollow cylindrical shape having one end Wa and the other end Wb, and has an enlarged diameter portion P4 having an enlarged inner diameter and an outer diameter at the one end Wa. Between the one end Wa and the other end Wb, there is a thin portion P1 thinner than the one end Wa and the other end Wb. The other end portion Wb has a flared portion P5 with enlarged inner and outer diameters. A thick portion P3 is provided between the thin portion P1 and the flared portion P5. Since the thick portion P3 has the same outer diameter as the thin portion P1 and a smaller inner diameter than the thin portion P1, the thick portion P3 is thicker than the thin portion P1. The thick portion P3 has an outer diameter dimension and an inner diameter dimension smaller than those of the flared portion P5. The thick portion P3 has the same outer diameter as the raw pipe W and an inner diameter that is substantially the same as or slightly smaller than that of the raw pipe W. The differential thickness pipe P has a longer overall length than the raw pipe W before processing.

According to the manufacturing method of the differential thickness tube according to the present embodiment described above, the same effects as those of the third embodiment can be obtained. In addition, according to the present embodiment, since the enlarged diameter portion P4 is formed and engaged with the enlarged diameter recessed portion 111x, pushing the plug 20 causes one end portion of the blank tube W to be enlarged in diameter and engaged with the enlarged diameter recessed portion 111x. can be stopped. In this case, since both the locking at the position of the one end Wa of the blank pipe W and the application of the reaction force at the other end Wb can be performed on the blank pipe W, ironing with a higher ironing rate can be performed.

[Fifth embodiment]
FIG. 6 is a view for explaining each step of the manufacturing method of the differential thickness pipe according to the fifth embodiment of the present invention in the order of (a) to (b), and includes the axis of the differential thickness pipe manufacturing apparatus. It is sectional drawing seen in the cross section.
First, an apparatus for manufacturing a tube with different thickness according to the present embodiment (hereinafter referred to as "ironing apparatus") will be described.
The ironing apparatus of the present embodiment is an apparatus for manufacturing a tube P having a different thickness from a blank tube W having a hollow cylindrical shape. As shown in FIG. 6( a ), the ironing device includes a die 210 , a plug 20 , a plug driving device (not shown), and a reaction force applying section 230 .

The die 210 has a housing portion 211 having an axis CL and is fixedly arranged at a fixed position.
The accommodation portion 211 is a columnar space corresponding to the outer diameter of the blank tube W. As shown in FIG. The accommodating portion 211 has an inner diameter dimension that is approximately the same as the outer diameter dimension of the base pipe W. As shown in FIG. The length dimension of the accommodation portion 211 along the axis CL is longer than the length dimension of the blank tube W. As shown in FIG. One end side of the housing portion 211 is an insertion port 211 a for the raw tube W, and the other end side of the housing portion 211 is an insertion port 211 b for the reaction force application portion 230 .

Since the plug 20 and the plug driving device have the same configurations as those of the first embodiment, the same reference numerals are used and the description thereof is omitted.

The reaction force application unit 230 includes a jig 231, a shaft 232, a hydraulic drive device (not shown), and a control device (control unit, not shown).
A jig (second jig) 231 is a columnar part having an outer diameter dimension substantially equal to the inner diameter dimension of the housing portion 211 and is arranged in the housing portion 211 so as to be freely advanceable and retractable.
One end of the shaft 232 is fixed to the back side of the jig 231 . The shaft 232, the jig 231, and the housing portion 211 share the axis CL.
The hydraulic drive device (biasing portion) is attached to the other end of the shaft 232 and hydraulically moves the shaft 232 back and forth along the axis CL. The hydraulic drive device includes a hydraulic sensor (not shown, measuring section) that measures hydraulic pressure.
The control device acquires the hydraulic pressure measured by the hydraulic pressure sensor and controls the operation of the hydraulic drive device according to the measured value. More specifically, the pressing force that the jig 231 receives from the other end Wb of the blank pipe W is obtained from the increase in hydraulic pressure, and control is performed to drain the oil so that the hydraulic pressure is maintained within a certain range. As a result, the reaction force against the movement from the one end Wa to the other end Wb along the longitudinal direction of the raw pipe W in the housing portion 211 is within a certain range. can be given as

A method for manufacturing a pipe having a different thickness using the ironing apparatus having the above-described configuration will be described below. As shown in FIGS. 6(a) and 6(b), the method for manufacturing a tube with different thickness according to the present embodiment is a method for manufacturing a tube with different thickness P from a hollow cylindrical base tube W, and includes an ironing process. have
In this ironing process, first, as shown in FIG. At this time, the end surface of the other end portion Wb of the blank tube W is arranged so as to abut on the surface of the jig 231 . At this point, the end face of the blank tube W has not yet been given a reaction force. The end face position of the one end Wa of the blank tube W is the same as the insertion opening 211a of the housing portion 211, or is located on the back side of the insertion opening 211a. Further, the base tube W is arranged coaxially with the accommodating portion 211 so as to share the axis line CL.

After arranging the blank tube W, as shown in FIG. 6B, the plug 20 is inserted from one end Wa of the blank tube W, and the plug 20 is further pushed toward the other end Wb for ironing. This ironing process is performed while applying a reaction force to the other end portion Wb of the raw pipe W against the movement of the raw pipe W along the longitudinal direction from the one end portion Wa toward the other end portion Wb. Specifically, the axial force applied to the blank tube W by the plug 20 is received by the hydraulic drive device via the jig 231 and the shaft 232 . The oil pressure sensor measures oil pressure and sends the measurement to the controller. When the measured hydraulic pressure is higher than a predetermined range, the control device increases the retreat speed of the jig 231 by increasing the flow rate of oil drawn from the hydraulic cylinder. On the other hand, when the measured hydraulic pressure is lower than the predetermined range, the retreat speed of the jig 231 is decreased by decreasing the flow rate of the oil extracted from the hydraulic cylinder. With this feedback control, the jig 231 can be retracted so that the blank tube W always receives a constant reaction force at the other end Wb. Therefore, since ironing is performed while supporting the blank tube W by applying a constant reaction force to the other end Wb, the blank tube W can be reliably fixed in the die 210 even if the pressing force of the plug 20 is increased. Therefore, the raw tube W can be prevented from slipping in the die 210, and the ironing rate can be increased.

When the plug 20 is pushed into the raw pipe W with the raw pipe W fixed, the inner diameter of the raw pipe W is expanded by the plug 20 and becomes substantially the same as the outer diameter of the base 21 of the plug 20 . A portion of the blank tube W whose inner diameter is expanded becomes a thin-walled portion P1 that is thinner than the state before processing.
The other end portion Wb of the blank pipe W expands within the housing portion 211 as the wall thickness is reduced by ironing. At this time, the other end portion Wb of the raw pipe W continues to be supported by the reaction force applying portion 230, so that the fixed state of the raw pipe W can always be maintained. Therefore, the thin portion P1 can be formed without the position of the one end portion Wa of the blank tube W being largely displaced. By stopping the pushing of the plug 20, the extension of the other end portion Wb is stopped. The end face of the other end Wb does not protrude outside the die 210 .

Through the steps described above, a tube P having a different thickness described below can be formed from the blank tube W.
The differential-thickness pipe P has a hollow tubular shape having one end Wa and the other end Wb, and has a thin-walled portion P1 thinner than the other end Wb on the one end Wa side. Conversely, it has a thick portion P3, which is thicker than the thin portion P1, on the other end portion Wb side. Since the thick portion P3 has the same outer diameter as the thin portion P1 and a smaller inner diameter than the thin portion P1, the thick portion P3 is thicker than the thin portion P1. The thick portion P3 has the same outer diameter as the raw pipe W and an inner diameter that is substantially the same as or slightly smaller than that of the raw pipe W. The differential thickness pipe P has a longer overall length than the raw pipe W before processing.

As described above, the method for manufacturing a tube with different thickness according to the present embodiment is a method for manufacturing a tube with different thickness P from a hollow tubular blank W, and inserts the blank W into the die 210. , and while applying a reaction force to the other end Wb against the movement of the raw pipe W from the one end Wa toward the other end Wb along the longitudinal direction, the plug 20 is pushed from the one end Wa of the raw pipe W. There is an ironing step of pressing and ironing toward the other end portion Wb.
According to this method of manufacturing a tube with a different thickness, ironing is performed while applying a reaction force to the other end Wb to support the blank tube W. can be fixed securely. Therefore, since the blank pipe W can be prevented from slipping in the die 210, even if the ironing rate is high, the differential thickness pipe P can be manufactured with a high yield.

Further, the reaction force applying unit 230 of the present embodiment includes the hydraulic sensor that measures the pressing force applied to the jig 231 by the raw pipe W, and and the control device for controlling the reaction force of the hydraulic drive. According to this configuration, ironing is performed while feedback-controlling the retraction operation (at least one of retraction speed and retraction amount) of the jig 231 by the control device so that the pressing force obtained by the hydraulic pressure sensor is constant. can do

In the fifth embodiment, the reaction force is applied by hydraulic pressure. However, the modification shown in FIG. FIG. 7 is a cross-sectional view including the axis line CL of the tube P of different thickness.
In this modified example, the reaction force is applied by an elastic member 233 such as a spring instead of hydraulic pressure. During the ironing process, the plug 20 is pushed into the one end Wa of the blank tube W arranged in the housing portion 211, as in the fifth embodiment. Then, the blank tube W is ironed, and the other end Wb is elongated while receiving the reaction force of the elastic member 233 . Then, the pressing of the plug 20 is stopped and the plug 20 is pulled out, thereby completing the forming of the pipe P having a different thickness. The formed differential thickness pipe P has the same shape as the differential thickness pipe P shown in FIG. 6(b).

[Sixth embodiment]
FIG. 8 is a diagram for explaining each step of the manufacturing method of the differential thickness pipe according to the sixth embodiment of the present invention in the order of (a) to (c), and includes the axis of the differential thickness pipe manufacturing apparatus. It is sectional drawing seen in the cross section.
Hereinafter, the description will be made based on FIG. 8, but mainly the differences from the fifth embodiment will be described, and the same components as those of the fifth embodiment will be denoted by the same reference numerals. omitted.

As shown in FIG. 8( a ), the apparatus for manufacturing a tube with different thickness according to the present embodiment (hereinafter referred to as “ironing device”) is positioned at a position corresponding to one end Wa of the blank tube W in the housing portion 311 . , and has a diameter-enlarging recess 311x whose cross-sectional shape perpendicular to the longitudinal direction is larger than the outer diameter of one end Wa of the base pipe W. As shown in FIG.
The enlarged diameter concave portion 311x has a parallel portion 311x1 and a tapered portion 311x2. The parallel portion 311x1 has an inner diameter dimension larger than the outer diameter dimension of the blank tube W, and is a space with a constant inner diameter dimension at each position along the axis CL. The tapered portion 311x2 is a space that continues to the parallel portion 311x1 and tapers away from the parallel portion 311x1 along the axis CL. One end side of the tapered portion 311x2 is equal to the inner diameter dimension of the parallel portion 311x1, and the other end side is substantially equal to the outer diameter dimension of the blank tube W.

A method for manufacturing a pipe having a different thickness using the ironing apparatus having the above-described configuration will be described below.
In the ironing process of this embodiment, first, as shown in FIG. At this time, the end surface of the other end portion Wb of the blank tube W is arranged so as to abut on the surface of the jig 231 . The end face position of the one end Wa of the blank tube W is the same as the insertion opening 311a of the housing portion 311, or is located on the back side of the insertion opening 311a. Further, the base tube W is arranged coaxially with the accommodating portion 311 so as to share the axis line CL. Since the one end Wa of the base tube W is located inside the expanded diameter recess 311x, an annular gap is formed around the one end Wa.

After placing the tube W, as shown in FIG. 8(b), the plug 20 is inserted from one end Wa of the tube W and pushed. Then, the plug 20 expands the inner and outer diameters of the one end Wa of the blank tube W. As shown in FIG. As a result, the one end Wa of the blank tube W is expanded in diameter and fitted into the enlarged diameter concave portion 311x without any gap, and is locked.

Subsequently, as shown in FIG. 8(c), ironing is performed by further pushing the plug 20 toward the other end portion Wb. In this ironing process, as in the fifth embodiment, a reaction force is applied to the other end portion Wb of the raw pipe W to resist movement from the one end portion Wa toward the other end portion Wb along the longitudinal direction of the raw pipe W. It is done while In addition, in the present embodiment, the one end Wa of the blank tube W is engaged with the enlarged diameter concave portion 311x. Therefore, both locking at the position of the one end Wa of the blank tube W and application of reaction force at the position of the other end Wb can be performed.

When the plug 20 is pushed into the blank tube W in this state, the inner diameter of the blank tube W is expanded by the plug 20 and becomes substantially the same as the outer diameter dimension of the base portion 21 of the plug 20 . A portion of the raw pipe W whose inner diameter is expanded while the outer diameter is constrained by the inner diameter of the accommodating portion 311 becomes a thin portion P1 having a thickness smaller than that before processing.
The other end portion Wb of the blank pipe W expands within the accommodating portion 311 as the wall thickness is reduced by ironing. This elongation is absorbed by the retreat of the jig 231 . At this time, the other end portion Wb of the raw pipe W continues to be supported by the reaction force applying portion 230, so that the fixed state of the raw pipe W can always be maintained. Therefore, the thin portion P1 can be formed without the position of the one end portion Wa of the blank tube W being largely displaced. By stopping the pushing of the plug 20, the extension of the other end portion Wb is stopped. The end surface of the other end Wb does not protrude outside the die 310 .

Through the steps described above, a tube P having a different thickness described below can be formed from the blank tube W.
The differential thickness pipe P has a hollow cylindrical shape having one end Wa and the other end Wb, and has an enlarged diameter portion P4 having an enlarged inner diameter and an outer diameter at the one end Wa. Between the one end Wa and the other end Wb, there is a thin portion P1 thinner than the one end Wa and the other end Wb. The other end Wb has a thick portion P3. Since the thick portion P3 has the same outer diameter as the thin portion P1 and a smaller inner diameter than the thin portion P1, the thick portion P3 is thicker than the thin portion P1. The thick portion P3 has the same outer diameter as the raw pipe W and an inner diameter that is substantially the same as or slightly smaller than that of the raw pipe W. The differential thickness pipe P has a longer overall length than the raw pipe W before processing.

According to the manufacturing method of the differential-thickness tube according to the present embodiment described above, the same effects as those of the fifth embodiment can be obtained. In addition, according to the present embodiment, the enlarged diameter portion P4 is formed and engaged with the enlarged diameter recessed portion 311x. can be locked. In this case, since both the locking at the position of the one end Wa of the blank pipe W and the application of the reaction force at the other end Wb can be performed on the blank pipe W, ironing with a higher ironing rate can be performed.

Examples of application of the differential thickness pipe P manufactured by the manufacturing methods of the first to sixth embodiments described above include cross members, suspension members, frame members such as suspension arms, and perimeters and side impact bars in automobile parts. and other collision response parts, or driveline pipe parts such as drive shafts.
In frame members such as cross members, suspension arms, and suspension members, there are many cases in which a particular thickness is required for the mounting portions of other parts. It is possible to employ a light-weight structure in which the thickness is increased. Further, in these parts, there are cases where press working or bending is performed during post-processing for forming the thick portion into a predetermined shape. In this case, if the portion to be processed is thick and low in strength, it is easy to process, so the differential thickness pipe in each embodiment of the present invention can be preferably used.

The side impact bar is installed in the door panel and is a member that transmits impact energy in the event of a collision to both sides of the door. Therefore, if the central portion is thickened using the tubes of different thicknesses in each embodiment of the present invention, a lightweight structure can be achieved.
The perimeter is a frame member at the front of the vehicle body, and is a member that acts as a load transmission path in the event of a frontal collision. In addition, when bending the thick portion, it is easy to work if the thick portion has a low strength, so that the differential thickness pipe in each embodiment of the present invention can be preferably used.
In some cases, the drive shaft is subjected to spline processing on the differential thickness portion of the tube end, and since this portion is easy to process if it is thick and has low strength, the differential thickness tube in each embodiment of the present invention is preferably used. be able to.

Although the reaction force applying portions 30, 130, and 230 have been exemplified as forms for applying the reaction force to the other end portion Wb of the base pipe W, the forms are not limited to these. For example, in the embodiment of FIG. 1, the reaction force is applied by the tapered inner peripheral surface 12x that tapers off. A plurality of projections (not shown) may be arranged at equal angular intervals around the axis CL. In this case, when the plug 20 is pushed into the blank tube W, the other end portion Wb of the blank tube W rubs against each of the projections while extending, so that a reaction force can be applied to the blank tube W.

Further, in each of the above-described embodiments, in order to temporarily fix the blank tube W to be ironed in the die, for example, the taper portion 12 or the like, which has a linear inclined surface with a cross section including the axis line CL, is formed in the die or the jig. installed on the fixture. However, the inclined surface that applies the reaction force to the blank tube W is not limited to a linear shape. For example, as shown in the modified example of FIG. 9A, the inclined surface may have a curved shape (concave curved surface) that is concave when viewed in a cross section including the axis line CL. Conversely, as shown in a modified example of FIG. 9B, for example, the inclined surface may be curved (convex curved surface) that swells when viewed in a cross section including the axis CL. The same applies to each diameter-enlarged recess such as the diameter-enlarged recess 11x.
More specifically, the inner peripheral surface 12x in FIG. 1A, the first tapered portion 12A and the second tapered portion 12B in FIG. 2, the inner peripheral surface 12x and the tapered portion 11x2 in FIG. Each of the outer peripheral surface 143a in (a), the tapered portion 111x2 in FIG. 5(a), the outer peripheral surface 143a in FIG. 5(c), and the tapered portion 311x2 in FIG. That is, the inclined surface referred to in the present invention includes not only a linear shape but also a concave curved shape and a convex curved shape.

10, 10A, 10B, 110, 110A, 210, 310 Die 11x, 111x, 311x Diameter-enlarged concave portion 12x Inner peripheral surface (inclined surface)
13x inner peripheral surface (parallel surface)
20 plug 30, 130, 230 reaction force applying part 140 jig (first jig)
142a outer peripheral surface (parallel surface)
143a outer peripheral surface (inclined surface)
231 jig (second jig)
233 elastic member (biasing portion)
P Different thickness pipe P1 Thin portion P2 Constricted portion W Element pipe Wa One end Wb Other end

Claims (20)

A method for manufacturing a pipe with a different thickness from a hollow cylindrical base pipe having no flange ,
The one end of the raw pipe is placed in a die, and a reaction force is applied to the other end to resist movement from one end to the other end along the longitudinal direction of the raw pipe. A method for manufacturing a tube with a different thickness, comprising an ironing step in which the plug is further pushed in and ironed toward the other end. An inclined surface facing the other end of the base pipe is provided in the die,
2. The method of manufacturing a tube having a different thickness according to claim 1, wherein in the ironing step, the plug is pushed in while receiving the other end of the blank tube on the inclined surface. A parallel surface continuous with the inclined surface and along the longitudinal direction is provided in the die, and when the plug is pushed in in the ironing process, the other end portion of the blank pipe passes through the inclined surface. 3. The method of manufacturing a differential thickness pipe according to claim 2, wherein the portion is further moved along the parallel plane. 4. The method of manufacturing a tube with different thickness according to claim 2, wherein the inclined surface is formed within the die. 4. The method of manufacturing a tube having a different thickness according to claim 2, wherein said inclined surface is formed on a first jig disposed within said die. The ironing process according to any one of claims 1 to 5, wherein the reaction force is applied to the other end portion of the base pipe at a plurality of positions along the longitudinal direction. , the manufacturing method of the differential thickness pipe. A second jig is provided in the die with which the other end of the base pipe abuts,
In the ironing step, the plug is pushed in while receiving the other end of the blank pipe with the second jig and retracting the second jig along the longitudinal direction. The manufacturing method of the differential thickness pipe according to claim 1. In the ironing step, the pressing force applied by the blank tube to the second jig is measured, and the retreating operation of the second jig is controlled so that the pressing force falls within a predetermined range. The manufacturing method of the differential thickness pipe according to claim 7. A diameter-enlarging recess having a cross-sectional shape orthogonal to the longitudinal direction and having a larger outer diameter than the one end of the blank pipe is formed in the die at a position corresponding to the one end of the blank pipe,
9. The ironing process according to any one of claims 1 to 8, characterized in that the outer diameter of the one end portion of the blank tube is enlarged by pushing the plug in the ironing step so that the plug is engaged with the diameter-enlarged concave portion. , a method for manufacturing a tube with a different thickness. The differential thickness according to any one of claims 1 to 9, characterized in that the thickness reduction rate of the thin portion of the differential thickness pipe after the ironing process is in the range of 10% to 90%. A method of manufacturing a tube. The method for manufacturing a differential thickness pipe according to any one of claims 1 to 10, wherein the base pipe is a seamless steel pipe. A device for manufacturing a pipe with a different thickness from a hollow cylindrical base pipe without a flange ,
a die having an accommodating portion in which the blank tube is accommodated;
a plug that is inserted into and removed from one end of the base tube in the housing;
a reaction force applying portion that applies a reaction force to the other end portion of the raw pipe in the housing portion against movement from the one end portion toward the other end portion along the longitudinal direction of the raw pipe;
An apparatus for manufacturing a tube with a different thickness, comprising: 13. The apparatus for manufacturing a pipe with different thickness according to claim 12, wherein the reaction force applying portion is an inclined surface facing the other end of the blank pipe. 14. The apparatus for manufacturing a pipe with a different thickness according to claim 13, wherein the reaction force applying portion further has a parallel surface extending along the longitudinal direction and connected to the inclined surface. 15. The apparatus for manufacturing a tube with different thickness according to claim 13 or 14, wherein the inclined surface is formed within the die. further comprising a first jig disposed within the die;
15. The apparatus for manufacturing a tube with different thickness according to claim 13, wherein the inclined surface is formed on the first jig. 17. The apparatus for manufacturing a tube with different thickness according to any one of claims 12 to 16, wherein the reaction force applying section is arranged at a plurality of positions along the longitudinal direction. The reaction force applying section is
a second jig arranged in the die, facing the other end of the blank tube, and movable back and forth along the longitudinal direction;
a biasing portion that applies the reaction force to the second jig;
13. The apparatus for manufacturing a pipe with different thickness according to claim 12, characterized by comprising: The reaction force applying section is
a measuring unit that measures the pressing force applied by the blank tube to the second jig;
a control unit that controls the reaction force of the biasing unit so that the pressing force obtained by the measuring unit is within a predetermined range;
19. The apparatus for manufacturing differential thickness pipes according to claim 18, further comprising: A diameter-enlarging recess having a cross-sectional shape orthogonal to the longitudinal direction and having a larger outer diameter than the one end of the blank pipe is formed in the accommodating portion at a position corresponding to the one end of the blank pipe. The apparatus for manufacturing a tube with different thickness according to any one of claims 12 to 19.

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