JP2000000617A - Method and apparatus for forming cylindrical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a desired shape highly precisely in a short time at the time of forming a cylindrical member whose middle part is constricted. SOLUTION: By pressing core bars 27, 28 in both end parts of a base stock 6, the displacing part A and fixing part C of the base stock are restrained. Axial pressure is applied to the base stock 6 with the core bar 27, 28 and simultaneously relative rotation is applied to the displacing part A and fixing part C. Because the displacing part A and fixing part C are restrained with the core bar 27, 28, torsion is generated only in the deforming part B and the diameter is reduced toward the axial center. Moreover, by making the displacing part A and fixing part C approach as progressing diameter reduction by drawing, the deforming part B are inserted between the tip faces of the core bars 27, 28 and the cylindrical member 4 whose middle part is constricted is formed. At this time, by mutually adjusting the rotational speed and approaching speed of the displacing part A and fixing part C of the base stock 6, strain generated in the deforming part B is finely adjusted and the occurrence of wrinkles or the like is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of drawing a central portion of a cylindrical member or the like.

[0002]

2. Description of the Related Art A vehicle suspension member 1 shown in FIG. 10 is fixed to a body via a cushion. Engine, suspension,
By attaching a steering gear or the like to the suspension member 1, there is an advantage that noise, vibration, and the like in the room can be reduced. The illustrated suspension member 1 uses four cushions,
Each of them is arranged in a portion indicated by reference numeral 2.

FIG. 11 shows a cross section of the cushion 3 fixed to the suspension member 1. The illustrated cushion 3 is formed by fitting a rubber bush 5 into a cylindrical member 4 having a narrowed central portion. By the way, conventionally, when molding a cylindrical member whose central portion is constricted like the cylindrical member 4, the following method has been adopted. FIG. 12 shows the procedure. First, the pipe 6 having an inner diameter D _Z shown in FIG.
On the other hand, as shown in FIG. 12 (b), and the central portion 6a bordering subjected to diameter reduction of the internal diameter D ₀ to the end 6b (first step). Subsequently, after annealing (second step), FIG.
The end 6b is once reduced in diameter, leaving the center 6a as shown in FIG.
Is again expanded (third step). Finally, the central portion 6a is crushed by compressing in the axial direction (fourth step), and FIG.
A desired cylindrical member 4 shown in (d) is formed. Note that the inner diameters D ₀ , D ₁ , and D ₂ in each step maintain substantially the same value.

FIGS. 13 (a) and 13 (b) show another method for obtaining the cylindrical member 4. FIG. FIG. 13
(A) is a top view showing a state before and after processing, and shows a state before processing on the right side of the center line and a state after processing on the left side of the center line. FIG. 13B is a cross-sectional view showing a state before and after processing, and shows a state before processing on the right side of the center line and a state after processing on the left side of the center line. This technique is
By pressing a plurality of approach cams 7 simultaneously from the outside against the central portion 6a of the raw tube 6, the shape of the approach cam 7 is transferred to the central portion 6a of the raw tube 6. Therefore, the figure
A shape similar to 12 (c) can be obtained in one step. Thereafter, by compressing in the axial direction, a desired cylindrical member 4 can be obtained in the same manner as in FIG.

As another method, there is a method as shown in FIG. First, the raw tube 6 is rotated, and the spatula 8 and the like are pressed against the raw tube 6. Then, the central portion 6a of the raw tube is gradually drawn, and the drawing process is repeated while performing intermediate annealing, whereby the central portion 6a is gradually deformed to obtain a shape similar to that of FIG. 12 (c). . Thereafter, by compressing in the axial direction, a cylindrical member 4 similar to that shown in FIG. 12D can be obtained.

[0006]

As described above, various techniques have been devised for forming the cylindrical member 4 having a constricted central portion. Conventionally, each technique has the following problems. Was. First, the method shown in FIG. 12 requires four steps, and the steps include annealing, so that much time and labor are required for processing. FIG.
In the method shown in (1), since the leading end of the approach cam 7 has a shape after diameter reduction, the contact with the raw tube 6 becomes a point contact at the initial stage of processing, and the contact point gradually changes in the circumferential direction of the raw tube. It will move to. Therefore, it is difficult to make the shape after the diameter reduction into a uniform circular shape. Further, the method shown in FIG. 14 requires a plurality of spatula drawing steps and an annealing step, and also has a drawback that much time and labor are required for processing. As described above, when the cylindrical member 4 is used for the cushion 3, a plurality of cushions are required for one vehicle, and therefore, it is necessary to overcome the above-mentioned disadvantages in order to promote cost reduction of the vehicle. Had become.

The present invention has been made in view of the above problems, and has as its object to obtain a desired shape with high precision and in a short time in forming a cylindrical member having a narrowed central portion.

[0008]

According to the present invention, there is provided a method for forming a cylindrical member, comprising: forming a pair of mandrel having a desired shape on both ends of a thin cylindrical material; Press-fit and transfer the shape to both ends of the material, make at least one of the mandrel approach the other, and, according to the approach of the mandrel, at least one mandrel with respect to the other mandrel By rotating the material, the central portion in the longitudinal direction of the material is squeezed toward the center, and a portion of the material located between two mandrels is brought into close contact with the surface of the mandrel.

When a mandrel is press-fitted into both ends of the material, plastic deformation occurs in the material, and the shape of the mandrel is transferred to both ends of the material. In addition, the mandrel is used by utilizing springback accompanying the plastic deformation (a phenomenon in which, after a material is deformed by applying a force and then the force is removed, the material tends to return to its original shape due to the elasticity of the material). To restrain both ends of the material. Subsequently, the two mandrels are brought closer to the other mandrel, and an axial compressive stress is applied to the portion of the material restrained by the two mandrels. At this time, the portion tends to be deformed in the radially expanding direction, which is easily deformed. Therefore, by giving relative rotation to the two mandrels in response to the approach of the mandrel, the portion of the material located between the two mandrels is twisted to reduce the diameter in the axial direction. The diameter of the mandrel is further advanced by the torsion, and the shape of the mandrel is transferred to a portion located between the two mandrels by closely contacting the surfaces of the mandrels approaching each other.

A cylindrical member forming apparatus according to the present invention for solving the above-mentioned problems is provided with a pair of mandrels which are press-fitted into both ends of a thin-walled cylindrical material and transfer the shape to the material. It is characterized by comprising a clamp means and a drive means for causing the pair of clamp means to approach each other and generating relative rotation in synchronization with the approach.

According to the present invention, the shape of the mandrel is transferred to the end of the material by the mandrel when both ends of the material are clamped by the clamping means. Also,
When the pair of clamping means are brought close to each other by the driving means while both ends of the material are clamped, an axial compressive stress is applied to the material. Further, by generating a relative rotation in synchronization with the approach of the pair of clamping means, a portion of the material located between the two mandrels is squeezed, and the diameter of this portion is reduced in the axial direction. Then, the diameter of the mandrel is further advanced, and the shape of the mandrel is transferred to a portion located between the two mandrels by bringing the mandrel into close contact with the surfaces of the mandrels approaching each other.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, the same or corresponding portions as in the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

First, a method for forming a cylindrical member according to an embodiment of the present invention will be described with reference to FIG. In the following description, the raw tube 6 is referred to as a displacing part A, a deforming part B,
Think about it in three. First, the fixing portion C of the raw tube 6 is fixed at the position shown in FIG. On the other hand, the displacement portion A of the raw tube 6 approaches the fixed portion A and relatively rotates as described later. The deformable portion B passively changes its shape with a change in the relative position between the displacement portion A and the fixed portion C.

Here, the molding method will be described step by step. First, the displacement part A and the fixed part C of the raw tube 6 shown in FIG. 1A are clamped so that their diameters do not change in the following steps. Note that the deformed portion B is not particularly restricted. Subsequently, as shown in FIG. 1B, the displacement part A is made to approach the fixed part C.
Further, in synchronization with this, the displacement part A is rotated with respect to the fixed part C. Then, the deformed portion B is twisted and narrowed in the axial direction to reduce its diameter. Subsequently, when the displacement portion A is moved closer to and relatively rotated with respect to the fixed portion C, the deformed portion B is twisted between the displacement portion A and the fixed portion C as shown in FIG. To form a cylindrical member 4 having a narrowed central portion.

In the step shown in FIG. 1 (b), if the displacement portion A is brought close to the fixed portion C without being relatively rotated, only the compressive stress in the axial direction is applied to the deformed portion B. . Then, the deformed portion B is deformed in a direction that can be easily plastically deformed. In this case, as shown in FIG. 2, the deformed portion B is deformed in the radially expanding direction over the entire circumference. This phenomenon is caused by the fact that the compressive strain in the axial direction generated in the deformed portion B escapes in the circumferential direction, and the deformed portion B generates elongational strain in the circumferential direction. Therefore, if the outer periphery of the raw tube 6 is constrained by a sleeve or the like as shown in FIG. 3 so as not to cause deformation in the radially enlarged direction, irregular wrinkles occur in the deformed portion B as shown in the figure, and eventually the desired cylinder It becomes impossible to obtain the member 4.

FIG. 4 shows a molding apparatus 11 for performing a molding method according to an embodiment of the present invention.
The molding device 11 includes a housing 13 provided on a base 12, and a rotating table 14 and a lifting guide 15 therein. A motor 16 is provided inside the base 12 as a power source for the turntable 14, and drives the turntable 14 via a speed reducer 17. An actuator 18 as a power source of the elevating guide 15 is fixed to a top surface of the housing 13. In addition,
The turntable 14 is supported on the base 12 via a thrust bearing 19, and does not perform a lifting operation. The elevating guide 15 is supported by the housing 13 via the linear plate 20, and does not rotate.

At the center of the rotary table 14 and the elevating guide 15, cylindrical spools 21, 22 are erected so as to face each other. Further, the lifting table 2 is movable in the axial direction (vertical direction in FIG. 4) with the spools 21 and 22 as axes.
3, 24 are provided. The elevating tables 23 and 24 are normally urged by springs 25 and 26 toward the distal ends of the spools 21 and 22. The lifting tables 23 and 24 have a movable range of the stroke S with respect to the spools 21 and 22, respectively.

FIG. 5 shows the mandrels 27 and 28 and the raw pipe 6 provided at the distal ends of the spools 21 and 22 for each processing step. The mandrel 27, 28 has a stroke S as shown in the figure.
And press-fitting margins 27a and 28a having substantially the same length as the above. Press-in fee 27
The diameters of a and 28a are obtained by further increasing the diameter by about 0.5% from the diameter in consideration of the pipe inner diameter error.

A procedure for forming the raw tube 6 into a desired cylindrical member 4 using the forming apparatus 11 will be described below with reference to FIGS.

First, as shown in FIG. 4, the raw tube 6 is placed on the elevating table 23 in alignment with the spool 21. Subsequently, the lifting guide 15 is lowered, and the spool 22 is also placed on the upper end of the raw tube 6.
Abut on the tip of the lifting table 24. This state is shown in FIG. Subsequently, when the lifting guide 15 is lowered, the mandrels 27 and 28 are press-fitted into the upper and lower ends of the raw tube 6. At this time, the elevating tables 23 and 24 (FIG. 4) move with respect to the spools 21 and 22 by a stroke S, respectively. FIG.
As shown in (b), press-fitting margins 27a and 28a of the mandrel are completely press-fitted into the upper and lower ends of the raw tube 6, and plastic deformation occurs. The portion where the plastic deformation has occurred is restrained by the mandrels 27 and 28 by the action of the springback. The constrained portions at both ends of the raw tube 6 become the displacement portion A and the fixed portion C described with reference to FIG. In addition, a portion where plastic deformation has not occurred at this time is the deformed portion B described with reference to FIG. The lifting tables 23 and 24 may be provided with separate clamps for pressing the displacement portion A and the fixed portion C from outside the raw tube 6 to the mandrels 27 and 28. When the molding apparatus 11 is used, the relative rotation of the displacement part A and the fixed part C is brought about by the rotation of the fixed part C (rotary table 14).

Subsequently, while lowering the elevating guide 15,
The rotary table 14 is driven to rotate. Then, the raw tube 6 is shown in FIG.
As shown in (c), the deformed portion B is twisted to reduce its diameter. At this time, the rotational speed of the fixed portion C and the descending speed of the displacement portion A are adjusted with each other to finely adjust the distortion generated in the deformed portion B so that the deformed portion B does not have molding defects such as wrinkles. can do. Since the displacement portion A and the fixed portion C are restrained by the mandrels 27 and 28, no deformation occurs, and the shape shown in FIG. 5B is maintained.

Further, while lowering the elevating guide 15,
By rotating and driving the rotary table 14, FIG.
As shown in (1), the deformed portion B can be folded by sandwiching it between the end surfaces of the mandrel 27, 28. Then, the desired cylindrical member 4
Is completed. After this, raise the elevating guide 15
Separate 7, 28, and remove cylindrical member 4 from the mandrel.

As shown in FIG. 6, a protrusion 29 having a predetermined diameter is provided at the tip of the mandrel 28 so that the protrusion 29 can be engaged with the tip of the mandrel 27. Protrusion 29
And the processing accuracy can be improved. Further, FIGS. 7 and 8 show examples in which the shapes of the mandrel 27 and 28 are changed, respectively. However, by changing the shape of the mandrel, cylindrical members 4 of various shapes can be formed in the same processing procedure. Can be molded. Further, if the cylindrical member 4 formed by the present apparatus is cut at the center as shown in FIG. 9, it can be used as a part for piping (a nipple with a step) or the like, and is replaced with a part which has been conventionally formed by diameter reduction processing. It is also possible.

The operation and effect obtained from the embodiment of the present invention having the above configuration are as follows. In the present embodiment, displacement parts A and fixed parts C of the material 6 are restrained by press fitting mandrels 27 and 28 into both ends of the material 6. And
Axial pressure is applied to the material 6 by the mandrels 27 and 28, and at the same time, relative displacement is applied to the displacement portion A and the fixed portion C. Displacement part A
Further, since the fixing portion C is restrained by the mandrels 27 and 28, only the deformed portion B is twisted to reduce the diameter in the axial direction. Further, by causing the displacement portion A and the fixed portion C to approach each other while advancing the diameter reduction by the aperture, the deformation portion B
Can be sandwiched between the end surfaces of the mandrels 27 and 28 to form the cylindrical member 4 having a narrowed central portion. At this time, the rotational speed and the approach speed of the displacement portion A and the fixed portion C of the material 6 are mutually adjusted to finely adjust the distortion generated in the deformed portion B,
It is possible to prevent molding defects such as wrinkles from occurring in the deformed portion B. Further, since the deformed portion B also comes into close contact with the mandrel 27, 28, high dimensional accuracy can be obtained also in this portion.

As described above, if the cylindrical member 4 is formed according to the embodiment of the present invention, it is not necessary to perform a heat treatment such as annealing in the middle, and the raw material 6 is simply put into the forming device 11 once, and the desired cylindrical member is formed. The member 4 can be formed. Therefore, shortening the processing time while maintaining high component accuracy,
Costs can be reduced.

[0026]

According to the present invention, the following effects are obtained. According to the method for forming a tubular member according to claim 1 of the present invention, in forming a tubular member having a narrowed central portion, a processing procedure including a plurality of steps is not required as in the related art, and A desired shape can be obtained with high accuracy and in a short time without performing heat treatment such as annealing. Therefore, it becomes possible to reduce the manufacturing cost of a desired cylindrical member.

Further, according to the cylindrical member forming apparatus according to the second aspect of the present invention, the cylindrical member whose central portion is narrowed can be removed with high precision and in a short time only by charging the material into the apparatus once. It is possible to mold. Therefore, it becomes possible to reduce the manufacturing cost of a desired cylindrical member.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining the concept of a method for forming a tubular member according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a product shape in a case where processing is performed without twisting a raw tube.

FIG. 3 is a cross-sectional view showing a product shape when the outside of the raw tube is restrained and the raw tube is processed without being twisted.

FIG. 4 is a schematic sectional view showing an apparatus for performing a method for forming a tubular member according to an embodiment of the present invention.

FIG. 5 is a schematic view showing a procedure for forming a cylindrical member using the apparatus shown in FIG.

FIG. 6 is a schematic diagram showing an application example of the mandrel shown in FIG. 5;

FIG. 7 is a schematic diagram showing another application example of the mandrel shown in FIG. 5;

8 is a schematic diagram showing another application example of the mandrel shown in FIG.

FIG. 9 is a schematic view showing an example of use of a cylindrical member formed according to the embodiment of the present invention.

FIG. 10 is a perspective view showing a suspension member of an automobile.

FIG. 11 is a sectional view showing a cushion fixed to the suspension member of FIG. 10;

FIG. 12 is a schematic view showing a procedure of a conventional method for forming a cylindrical member.

FIG. 13 is a schematic diagram showing a procedure of a conventional cylindrical member forming method different from FIG.

FIG. 14 is a schematic view showing a procedure of still another conventional method for forming a cylindrical member.

[Explanation of symbols]

 4 Cylindrical member 6 Element tube 27 Mandrel 28 Mandrel A Displacement part B Deformation part C Fixing part

Claims (2)

[Claims] 1. A pair of mandrel having a desired shape is press-fitted into both ends of a thin cylindrical material, and the shapes are transferred to both ends of the material, and at least one core of the mandrel is formed. Approaching the other mandrel, and rotating at least one mandrel with respect to the other mandrel in accordance with the approach of the mandrel so that the center in the longitudinal direction of the material is moved toward the center. A method for forming a tubular member, comprising: drawing and bringing a portion of the material between two mandrels into close contact with a surface of the mandrel. 2. A pair of clamp means provided with a mandrel which is pressed into both ends of a thin cylindrical material and transfers the shape to the material, and the pair of clamp means are brought close to each other and synchronized with the approach. And a driving means for generating relative rotation by means of a cylindrical member.