JP2001137964A - Manufacturing method of thin cylindrical body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a thin cylindrical body having reduced variance in out-of-roundness by ironing from a metal stock tube so as not to likely cause manufacturing stop as well as buckling in pulling out a punch when a metal stock tube and a forming cylindrical body are thin. SOLUTION: A protrusion part 10b of an ironing punch 100 is inserted into a space part 7c of a metal tube 1 or an intermediate ironing body 21 in which a fold back part 7b having a circular space part 7c is formed to the inner side of one of opening ends and then ironing is conducted. In this case, a double ironing ring 55 only having a front side ironing ring 57 and a back side ironing ring 56, in which the front side ironing ring 57 and the back side ironing ring 56 are arranged so that while ironing with the front side ironing ring 57, the back side ironing ring 56 conducts ironing as well, or the double ironing ring 55 arranged at the most front end together with ironing rings of one or more are used. After the ironing punch 100 is pulled out from a final ironing formed part 28, both end parts of the final ironing formed body 28 are trimmed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin metal cylinder, and more particularly to a method for manufacturing a thin metal cylinder from a cylindrical metal tube or a cylindrical metal tube by ironing. About.

[0002]

2. Description of the Related Art As a method for producing a thin-walled cylindrical body such as a photosensitive drum base material used for an image forming apparatus such as a copying machine or a printer, the surface of which is smooth and has a high roundness from a cylindrical tube.
A method of forming a curled portion having a short sectional length with a central angle of about 90 degrees at one open end of the raw tube, pressing the tip of the punch against the curled portion, and performing ironing with a single die. It has been proposed (JP-A-7-68326). According to this method, the wall thickness of the base tube as described in the example of the above publication is as large as 3.0 mm, and the wall thickness of the cylindrical body after ironing is also compared with 1.1 mm (reduction ratio: 62.3%). If the target is thick, a satisfactory product can be obtained by roughening the punch surface.

However, recently, it has been proposed to use a flexible photosensitive drum in an image forming apparatus such as a copying machine (for example, Japanese Patent Laid-Open No. 10-10823). In this case, a thin-walled cylindrical photosensitive drum substrate having a small thickness (for example, 20 to 200 μm) and a relatively long thickness (for example, about 25 to 50 cm) is used. In order to manufacture an ultra-thin thin-walled cylindrical body by ironing as described above, if the wall thickness of the raw tube is reduced or the ironing rate at one time is increased,
During ironing, the curled part cannot withstand the load caused by the tip of the punch, the curled part is deformed and the punch comes off,
A problem that the productivity is lowered due to the breakage of the tool or the production stoppage is likely to occur.

Further, when the thin cylindrical body formed as described above is long, as shown in the above-mentioned Japanese Patent Application Laid-Open No. 7-68326, a stripping device (stopper 3 shown in FIG. ), When the punch is pulled out, the pull-out resistance is large, so that the vicinity of the opening buckles or the roundness decreases, the trim length near the opening increases, and the product yield decreases. Or the specified length of the photosensitive drum cannot be obtained.
In addition, when ironing is performed by a single die as described above, it has been found that there is a problem that the circularity of each thin cylindrical body varies greatly even if the extraction is satisfactorily performed.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for ironing a metal tube without the risk of damaging a tool or stopping production even when the thickness of the metal tube and the formed thin cylindrical body are thin. It is an object of the present invention to provide a method for producing a relatively long thin cylindrical body. The present invention further provides a method for manufacturing a relatively long thin cylinder from a metal tube by ironing, which does not cause buckling in the vicinity of the opening when the punch is extracted from the formed thin cylinder. The purpose is as follows. Another object of the present invention is to provide a method of manufacturing a relatively long thin cylinder from a metal tube by ironing, which has a small variation in roundness for each of the thin cylinders manufactured next. .

[0006]

According to a first aspect of the present invention, there is provided a method of manufacturing a thin-walled cylindrical body, wherein an inward flange portion is provided at an inner surface of one open end of a cylindrical metal pipe or at one open end thereof. On the inner surface side of the opening of the cylindrical metal tube having a cylindrical shape, a folded portion having an annular space portion is formed, and a hollow cylindrical protrusion of an ironing punch is inserted into the space portion, and the folded portion is formed. Engage and push the ironing punch forward, have front ironing ring and rear ironing ring, front ironing ring and rear ironing so that ironing with rear ironing ring is performed while ironing with front ironing ring The ironing molding is formed by ironing only the double / ironing ring provided with the ring, or by cooperating with the double / ironing ring arranged at the foremost end and one or more ironing rings. After extracting the Rashigoki punches, characterized by trimming the ends of the ironing element.

As the metal, aluminum, aluminum alloy, low carbon steel, tinplate, nickel-plated steel plate, stainless steel, copper, brass, nickel and the like are appropriately adopted. For example, as described in Example 2 of paragraph 0052 below, a cylindrical metal tube having an inward flange portion has a circular hole formed at the bottom of a drawn or redrawn formed body formed from a blank. Can be obtained.
The folded portion has a space inside the tip end (end face) until it is located on a plane connecting the lower ends of the side wall portions having a straight cross section or on the other open end or the opening side with respect to this plane. Refers to a portion that is folded back without wrinkles. The thickness of the thin cylinder is usually 0.05 to 1.0 mm.

In the case of the invention according to the first aspect, the hollow cylindrical projection of the ironing punch is inserted into the space and engaged with the folded portion to perform ironing. Since it is equal to the thickness of the metal tube or blank, it is thick, and the folded section has a large section modulus. Therefore, at the time of ironing, the folded portion is unlikely to be deformed by the load of the projection of the ironing punch, and the ironing punch is less likely to come off due to this deformation. For this reason, breakage of the tool and production stoppage due to the removal of the punch hardly occur.

Since the ironing formed body is provided with the folded portion, after the ironed formed body is formed, a finger of a stripper device is engaged with the end face of the folded portion, and the ironing punch can be extracted from the ironed formed body. Since the folded portion is thick and has a large section modulus, the ironing punch can be extracted even if the frictional resistance when the ironing punch is pulled out from the ironing molded body is large. In this case, since the finger does not engage with the opening end surface of the ironing formed body, the opening end does not buckle even if the extraction resistance is large.

A double having a front ironing ring and a rear ironing ring, wherein the front ironing ring and the rear ironing ring are arranged so that ironing is performed on the rear ironing ring during ironing with the front ironing ring. -Ironing is performed only by the ironing ring or by the cooperation of the double ironing ring and one or more ironing rings arranged at the front end. In other words, during ironing with the front ironing ring, ironing is performed with the rear ironing ring, so that the material flow in the circumferential direction of the ironing formed body at the approach side entrance side of the front ironing ring is suppressed by the rear ironing ring. The flow is mainly directed in the axial direction. As a result, the roundness of the ironed compact is improved, and the variation in roundness of each thin cylindrical body is reduced. Since the roundness is not 0, the cross section is usually very slightly elliptical, but the major axis direction of the ellipse is almost aligned in each of the cross sections in the height direction. It is thought that the roundness when the end body (see 60 in FIG. 20) is fitted into both open ends as an intermediate member for attaching the thin cylinder to the image forming apparatus is improved.
In addition, the variation in roundness of each thin cylinder is reduced.

[0011] In the invention according to claim 2, the folded portion is
The method for producing a thin-walled cylindrical body according to claim 1, comprising an annular groove. The annular groove is the tip (end face) of the folded part
Is on a plane connecting the lower ends of the side walls of the straight section. The cross-sectional shape of the annular groove can be an appropriate shape such as a semicircular shape or a semi-elliptical shape. The annular groove has a larger section modulus than the curl. The invention according to claim 3 is the method for manufacturing a thin-walled cylindrical body according to claim 1, wherein the folded portion comprises an annular groove portion and a short cylindrical portion or a trapezoidal portion connected to the annular groove portion. The short cylindrical shape refers to a short cylindrical shape or a shape close to a short cylindrical shape. Since the short cylindrical portion or the trapezoidal portion is connected to the annular groove, the section modulus is larger than in the case of the invention according to claim 2. If the short cylindrical parts are connected,
The section modulus is larger than when the trapezoids are connected.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a drawing showing a state before a first step for forming a folded portion at an upper end of a metal pipe is performed. In FIG. 1, reference numeral 1 denotes a metal tube cut from a long metal pipe to a predetermined length at a right angle in the axial direction. Reference numeral 2 denotes a die, which comprises a cylindrical base 2a and a molded part 2b fixed to the base 2a. Molding part 2
b is a cylindrical base 2b1 whose height is slightly larger than half the height of the base tube 1, and a tapered tapered portion 2 connected to the base 2b1.
b2. The outer diameter of the outer peripheral surface of the cylindrical base 2b1 is determined to be extremely slightly smaller than the inner diameter of the metal tube 1 so that the metal tube 1 can be inserted almost exactly. The taper angle of the tapered portion 2b2 is extremely small, about 1 to 5 degrees. An annular projection 2c having a tapered portion 2b2 as an outer peripheral surface is formed at the tip of the molded portion 2b. Annular projection 2c
Is a curved portion 2c1 having a semicircular cross section connected to the tapered portion 2b2.
And a short cylindrical portion 2c2 connected to the inner end of the curvature portion 2c1
It has.

The bending tool 3 which can be moved up and down is provided with a concave portion 3a and an air vent hole 3b formed on the upper portion of the concave portion 3a. The concave portion 3a has a tapered portion 3a1 having a large taper angle for facilitating introduction of the metal pipe 1 from below, and a cylindrical portion 3a having a very small taper angle connected to the tapered portion 3a1.
2. A curved portion 3a3 connected to the cylindrical portion 3a2 and a slightly radially upwardly inclined through hole 3 connected to the curved portion 3a3.
b, an annular upper surface 3a4 extending to the lower end of the peripheral surface. The metal tube 1, the die 2, and the bending tool 3 are coaxially arranged by a device (not shown) so that the metal tube 1 is located at an intermediate position as shown in the drawing.

After the metal tube 1 is lowered by a device (not shown) and extrapolated to the forming portion 2b of the die 2, the bending tool 3 is lowered by a device (not shown) to form the concave portion 3a.
Is inserted into the upper end portion of the raw tube 1 and the upper end portion is pressed until the inward flange portion 4 whose upper end portion is directed inward in the radial direction is formed by the curvature portion 3a3 and the annular upper surface portion 3a4 (not shown). Press. FIG. 2 shows a state after the pressing is completed, and an inward flange portion 4 is formed at an upper portion of the raw tube 1.

FIG. 3 is a view showing a state before a final step for forming a folded portion at the upper end of the metal tube is performed. Reference numeral 2 denotes a die shown in FIG. 1, and a raw tube 1 having an inward flange portion 4 formed thereon is supported and arranged by a device (not shown). A folded portion forming tool 5 is disposed above the metal tube 1.

The folded portion forming tool 5 has a folded portion forming concave portion 6. The folded portion forming concave portion 6 includes an introducing trapezoidal portion 6a extending upward from the lower surface of the folded portion forming tool 5 at an extremely small taper angle, a curved portion 6b having a semicircular cross section connected to an upper end of the trapezoidal portion 6a, A short cylindrical portion 6c connected to the inner end of the curvature portion 6b and a flat portion 6d perpendicular to the axial direction connected to the short cylindrical portion 6c via the curvature portion are provided. An air vent 6e extends in the axial direction through the center of the flat portion 6d. The inside diameter of the upper end of the trapezoid 6a is
Is set substantially equal to the outer diameter of. The radius of curvature of the curvature portion 6b is set to be equal to (the radius of curvature of the curvature portion 2c1 of the die 2 + the thickness of the metal tube 1). Short cylindrical part 6c
Is desirably slightly longer than the maximum length of the short cylindrical portion 7b2 within a range in which the formed folded portion 7b does not wrinkle.

After lowering the metal tube 1 having the inward flange 4 formed thereon by a device (not shown) and externally inserting the metal tube 1 into the forming portion 2b of the die 2, the tool 5 for forming the folded portion is lowered by a device (not shown). Then, after the concave portion 6 is extrapolated to the upper end portion of the raw tube 1, the flange portion 4 is pressed by a pressing tool (not shown) so that the flange portion 4 is joined to the annular projection 2 c of the die 2 and the short cylindrical portion of the folded portion forming tool 5. By the cooperation of 6c, the flange portion 4 is bent until it hangs down to form a folded body 7b having a curvature portion 7b1 and a short cylindrical portion 7b2, and an ironing element 7 having a side wall portion 7a.

FIG. 4 shows a state after the pressing is completed. In FIG. 4, the metal tube 1 has an ironing body 7 having a folded portion 7b composed of a curvature portion 7b1 and a short cylindrical portion 7b2, and a side wall portion 7a.
Is formed. FIG. 5 shows the ironing element 7 shown in FIG. 4 pulled out of the die 2 and inverted so that the folded-back portion 7b is located at the bottom. A space 7c is formed between the lower part of the side wall 7a and the folded part 7b.

The ironing of the ironing element 7 can be performed in one step if the stroke of the punch of the ironing device is sufficiently long. For example, when ironing is performed only with the double ironing ring 55, it is performed in one step. However, when the stroke is short, ironing may be performed in several steps. In this case, the ironing with the double ironing ring 55 is performed in the last step. Next, an example in which ironing is performed in two steps will be described. FIG. 6 is a view showing a state immediately before the ironing element 7 is ironed in the first step. 1st ironing punch 10, ironing element 7, 1st ironing ring 11, 2nd ironing ring 1 from above
2, a third ironing ring 13 and a first stripper device 14 are arranged coaxially. Each ironing ring 1
1, 12, and 13 are held by a holding device (not shown) including a cooling lubricant injection device corresponding to each ironing ring. The number of ironing rings is appropriately determined according to the ironing rate and the total ironing rate of each ironing ring, the stroke length of the ironing device, and the like.

The outer diameter of the body 10a of the first ironing punch 10 is larger than the inner diameter of the side wall 7a of the ironing element 7 so that the body 10a can be fitted almost exactly into the side wall 7a of the ironing element 7. It is determined to be extremely small. The lower end of the first ironing punch 10 is a hollow cylindrical projection 10b. The outer surface 10b1 of the protruding portion 10b has a slightly lower inverted trapezoidal shape so that the first ironing punch 10 can be easily fitted. The lower end of the protruding portion 10b is set to have substantially the same shape and the same size as the space portion 7c so as to enter the space portion 7c of the ironing element 7 almost exactly. The height of the inner surface 10b3 of the protrusion 10b is
The height is determined to be larger than the height of the folded portion 7b of the ironing element 7 from the ground surface.

Although the distances L1 and L2 between the ironing rings 11, 12, and 13 are smaller in FIG. 6 due to the size of the drawing that can be illustrated, in practice the distances are much larger than those shown in FIG. large. That is, the interval L1 is set so that the ironing element 7 enters the ironing part 12b of the second ironing ring 12 after passing through the ironing part 11b (so-called short cylindrical land part) of the first ironing ring 11. Stipulated. Similarly, the interval L2 is determined by the intermediate ironing formed by the second ironing ring 12 (not shown).
After passing through the ironing part 12b of the second ironing ring 12, the ironing part 13 of the third ironing ring 13
b. Third ironing ring 1
3 and the distance L between the upper surface of the support 19 of the stripper device 14
3 is also set to be larger than the height of the intermediate ironing formed body 21 (see FIG. 7) formed by the third ironing ring 13.

FIG. 7 shows the intermediate ironing compact 21 in the second step.
3 is a diagram showing a state immediately before ironing. From above, a second ironing punch 100, an intermediate ironing molded body 21,
A fourth ironing ring 54, a rear ironing ring 56, a front ironing ring 57, and a second stripper device 114 are coaxially arranged.
Each ironing ring 54, 56, 57 is held by a holding device (not shown) provided with a cooling lubricant injection device corresponding to each ironing ring. In addition, the number of ironing rings is the ironing rate by each ironing ring and the total ironing rate,
The length of the stroke of the ironing device, the length of the final ironing formed body 28 to be formed, and the like are appropriately determined. For example, a fifth ironing ring (not shown) may be provided between the fourth ironing ring 54 and the double ironing ring 55.

The second ironing punch 100 has the same structure as that of the intermediate ironing formed body 21 except that the outer diameter of the body 10a is smaller according to the inner diameter of the ironing element body 7 being smaller than the inner diameter of the ironing element body 7.
The shape, structure, and the like are the same as those of the first punch 10. That is, the same portions as the symbols of the first punch 10 indicate the same portions. The interval L4 between the fourth ironing ring 54 and the double ironing ring 55 is such that the ironing portion 56b of the rear ironing ring 56 after the intermediate ironing formed body 21 has passed through the ironing portion 54b of the fourth ironing ring 54. It is set to enter. When ironing is performed in one step,
The distance between the third ironing ring 13 and the fourth ironing ring 54 is such that the intermediate ironing molded body 21 is the third ironing ring 1.
After passing through the third ironing portion 13b, it is set so as to enter the ironing portion 54b of the fourth ironing ring 54.

The distance L5 between the rear ironing ring 56 and the front ironing ring 57 is determined by the ironing part 56b of the rear ironing ring 56 during the final ironing by the ironing part 57b of the front ironing ring 57. The ironing ring 5 which is small enough to be machined, preferably
6 and the ironing ring 57 on the front side,
It is desirable that the cooling lubricant be as small as possible within a range where the cooling lubricant can be injected. Ironing part 56b and ironing part 5
The smaller the distance L6 between the ironing rings 7b, the more easily the material flow in the circumferential direction of the intermediate ironing formed body 21 at the approach portion 57a of the front ironing ring 57 is suppressed by the rear ironing ring 56. I will be heading. Therefore, the roundness of the final ironing compact 28 is improved, and the variation of the roundness of each final ironing compact 28 is reduced.

The distance L6 between the ironing portion 56b and the ironing portion 57b is usually preferably 10 to 50 mm. In the second stripper device 114, the same reference numerals as those in the first stripper device 14 indicate similar portions. Support 1 for front ironing ring 57 and stripper device 114
The distance L7 between the upper surfaces 9 is also set to be larger than the height of the final ironing compact 28 formed by the double ironing ring 55.

When the metal tube is made of aluminum or an aluminum alloy, it is preferable to use a lubricant having a kinematic viscosity at 40 ° C. of 15 to 150 mm ² / sec as a cooling lubricant in order to prevent breakage. When a water emulsion or an aqueous solution is used as a cooling lubricant, the kinematic viscosity is 30 to
It is preferable to dilute 300 mm ² / sec of lubricant to make a cooling lubricant.

In the above case, the approach angle α (see FIG. 7) of the approach portion of each ironing ring is preferably 2 to 10 degrees from the viewpoint of preventing breakage during ironing. The ironing rate of the front ironing ring 57 is 20 to 5
0%, ironing rate with rear ironing ring 56 is 10 to 50
%. If the ironing rate of the front ironing ring 57 is less than 20%, the roundness of the final ironing formed body 28 will be deteriorated, and if it is more than 50%, it will be easily broken. Similarly, if the ironing rate at the rear ironing ring 56 is smaller than 10%, the final ironing molded body 2
This is because the roundness of No. 8 is deteriorated, while if it is more than 50%, breakage is likely to occur.

FIG. 8 shows the protrusion 10 of the ironing punch 100.
7B shows a process in which the intermediate ironing body 21 is engaged with the folded portion 7b and advances in the direction of the arrow to form the intermediate ironing compact 21 in the final ironing compact 28. That is, FIG. 8 shows a state where the intermediate ironing formed body 21 is being ironed simultaneously by the ironing portions 56b and 57b. In this state, the flow of the material in the circumferential direction of the ironing formed body 21 at the approach portion 57a of the front ironing ring 57 causes the rear ironing ring 5
6, the flow is mainly directed in the axial direction, so that the roundness of the final ironing compact 28 is improved and the roundness of the final ironing compact 28 is small. Become.

FIG. 8 shows that the ironing punch 100 is further advanced in the direction of the arrow, and the end face 21a of the intermediate ironing molded body 21 is formed.
The state at the time when the user tries to leave the ironing portion 56b is shown.
In this state, the flow of the material in the circumferential direction of the ironing molded body 21 in the approach portion 57a is changed to the rear ironing ring 56.
Is hardly suppressed, the roundness of the portion of the final ironing compact 28 that is ironed in this state is reduced, and the variation of the roundness of this portion is large for each final ironing compact 28.

FIG. 8 shows that the end face 21a has an ironed portion 56b.
, And approaching the ironing portion 57. Also in this case, the roundness of the portion of the final ironing formed body 28 that has been ironed after this state is reduced, and the variation of the roundness of this portion is increased for each of the final ironed formed bodies 28. Therefore, the trimming on the opening end side of the final ironing formed body 28 is preferably performed at a position 58 slightly ahead of a portion in contact with the ironing portion 57b in FIG.

The double ironing ring may be of an integral structure as shown in FIG. In this case, the upper part 67 of the cooling lubricating liquid injection hole 66 of the double ironing ring 65 becomes the rear ironing ring, and the lower part becomes the front ironing ring 68. Reference numeral 67b denotes an ironing portion of the rear ironing ring, and reference numeral 68b denotes an ironing portion of the front ironing ring 68.

In FIG. 6, the stripper device 14 comprises:
The funnel-shaped core 16, which is surrounded by a plurality (n) of fingers 15 (n = 8 in the present embodiment) and can move up and down, moves the finger 15 radially inward with respect to the core 16. It has a ring spring 17 for elastically pressing and a cylindrical box-shaped holder 18 for holding the main part 15d of the finger 15. In the center of the bottom of the holder 18, a through hole 18b for inserting a core is formed.

As clearly shown in FIGS. 10 and 11,
The core 16 includes an upper inverted truncated cone 16a and a rod 16b connected to a lower end of the inverted truncated cone 16a. On the peripheral surface of the inverted truncated conical portion 16a, n longitudinal shallow grooves 16a1
Are formed at equal intervals in the circumferential direction. Rod part 16b
Is moved up and down at appropriate timing by a piston rod 20 of a cylinder (not shown) through a through hole 19a of the support 19. Accordingly, the inverted truncated conical portion 16a also moves up and down at appropriate timing. The finger 15 is almost exactly engaged with the vertical shallow groove 16a1, and has an inwardly protruding portion 15a having a slidable portion, and an outwardly projecting upper portion having an arcuate outer periphery and a flat claw portion 15b1 on the lower surface. A portion 15b is provided. The shape and size of the finger 15 are determined so that the claw portion 15b1 engages with the end face 7d of the folded portion 7b when the finger 15 is expanded (the state shown in FIG. 10).

An annular groove 15c for inserting the ring spring 17 is provided directly below the upper outwardly projecting portion 15b. The lower portion of the annular groove 15c has a main portion 15d whose outer peripheral surface has an arc-shaped cross section. When the core 16 descends and the finger 15 expands, the outer peripheral surface of the main portion 15d and the holder 18 are separated. Side wall 1
The inner surface 8a is configured to contact. Due to this contact and the force of pushing down the core 16 by the piston rod, the claw 15b1 does not rise even if a pushing force is applied to the claw 15b1.

From the state shown in FIG. 6, the formation of the thin cylindrical body 22 from the ironing element 7 is performed as follows. FIG. 6
In FIG. 7, the core 16 is in the raised position, the finger 15 is contracted, and the tip diameter of the claw portion 15b1 is extremely slightly smaller than the inner diameter of the short cylindrical portion 7b2 of the folded portion. First, the first punch 10 descends and advances, and the protrusion 10 b is inserted into the space 7 c of the ironing element 7.
In this state, the punch 10 continues to advance, and the side wall portion 7a of the ironing element body 7 is ironed by the first ironing ring 11, the second ironing ring 12, and the third ironing ring 13 to have a thicker wall. The intermediate ironing compact 21 is gradually reduced and lengthened, and the folded portion 7 b approaches the stripper device 14. However, as shown in FIG. 12, the thickness of the folded portion 7b remains thick while maintaining the original thickness.

When the first punch 10 further advances and reaches the bottom dead center, the ground portion of the folded portion 7b approaches the upper surface 19a of the support 19 as shown in FIG. Core 1 at the same time
6, the finger 15 expands, and the claw 15b1
Comes above the end face 7d of the folded portion. Punch 1 immediately
When 0 starts to ascend, the claw portion 15b1 engages with the end face 7d of the folded portion (FIG. 10), and the folded portion 7 stops at this position. As shown in FIG.
Is easily extracted from the intermediate ironing formed body 21. Thereafter, the finger 15 contracts and the intermediate ironing molded body 21 is pulled up.

Next, the ironing compact 21 is ironed by the apparatus shown in FIG. 7 in the same manner as described in paragraphs 0035 to 0036, and is longer than the intermediate ironing compact 21.
And the ironing compact 28 with a small diameter is formed. The final ironing molded body 28 is formed in the vicinity of the opening end and the folded portion 7b.
The nearby side wall is trimmed to form a thin cylindrical body 22 as shown in FIG. Trimming is performed by a wire electric discharge machining method or other known mechanical methods.

Without using the stripper device 114, a known stripper device 23 (for example, Japanese Patent Publication No.
In the case where the finger 24 is engaged with the opening end surface 28a of the final ironing molded body 28 and the punch 10 is pulled out using the above-described method, the following problem occurs. When the side wall portion 28b of the final ironing formed body 28 is extremely thin (for example, about 0.1 to 0.3 mm) and relatively long (for example, about 35 to 50 cm), the extraction resistance is large. Since the buckling deformation is likely to occur or the roundness is likely to be reduced, the trim length near the opening end 28c is increased, so that not only the yield is reduced but also the specified length of the product may not be obtained. There is. Further, there is a possibility that the opening end 28c cuts between the second ironing punch 100 and the finger 24 to damage the stripper device 23 and stop the production.

As shown in FIG. 17, the outer diameter of the projection 30b and the outer diameter of the portion 30c corresponding to the open end of the thin cylindrical body 22 'to be formed are slightly smaller than the outer diameter of the main portion 30a. By using the ironing punch 30,
It is possible to form a thin-walled cylindrical body 22 ′ whose both open ends are relatively thick and whose deformation resistance is improved. Reference numerals 31 and 32 indicated by alternate long and short dash lines indicate portions to be trimmed after the ironing punch 30 is extracted from the ironing molded body 28 '.

As shown in FIG. 18, through holes 10c and 16c having the same diameter and coaxially with the ironing punch 10 and the core 16 and the through holes 10c and 16c are inserted exactly, and can be moved up and down at a predetermined timing. When the punch 10 is extracted, the mandrel 25 is
Guides and supports the cantilevered punch 10
Of the ironing body 21 can be prevented from being distorted. While the punch 10 is descending, FIG.
0, the upper end of the mandrel 25 is located slightly above the upper surface of the core 16, and when the punch 10 starts to ascend, the upper end of the mandrel 25 has a through hole 10c as shown in FIG.
, The mandrel 25 rises at a higher speed than the punch 10 and supports the punch 10. Providing the mandrel 25 in this manner is particularly effective when the ironing machine is a horizontal type and the punch 10 is easily bent by gravity.

Reference numeral 26 denotes a flange mounted on the lower end of the core 16, 37 denotes a plurality of piston rods mounted on the lower surface of the flange 26, 38 denotes a cylinder, and 39 denotes a piston rod on its upper surface. Disk to be mounted, 39
a is an O-ring and 40 is a cylinder 3 through which the mandrel 25 is inserted.
8 is a central hole. Needless to say, the above configuration can be adopted also in the second step of FIG.

[0042]

EXAMPLE 1 An aluminum alloy pipe (JIS H40) having a length of 70.5 mm, an inner diameter of 66.1 mm and a wall thickness of 1.2 mm formed by extrusion and drawing.
80 alloy number 3003 H14) was used as the cylindrical raw tube 1. Using the tool shown in FIGS. 1 and 3, an ironing element 7 was formed from the raw tube 1 by the method shown in FIGS. 2 and 4. The inner surface radius of curvature r1 of the curved portion 7b1 of the folded portion 7b was 2.7 mm, and the height h of the short cylindrical portion 7b2 was 5.0 mm (see FIG. 5). The ironing element 7 was subjected to two steps of ironing with the ironing device shown in FIGS. 6 and 7. The reason for dividing into two times is that the stroke of the used press is restricted.

Punch 10 used for ironing in the first step
Of the body 10a (the surface roughness is the maximum height Ry = 0.26μ)
m) has an outer diameter of 66.05 mm and a curvature 1 of the protrusion 10 b.
The radius of curvature of Ob2 was 2.7 mm, and the height of the inner surface 10b3 from the ground contact portion was 28 mm. The ironing part 11b of the first ironing ring 11 and the ironing part 12 of the second ironing ring 12
b and the inside diameter of the ironing portion 13b of the third ironing ring 13 are 67.86 mm, 67.41 mm and 6 mm, respectively.
7.07 mm. The distance L1 between the first ironing ring 11 and the second ironing ring 12 is 150 mm, and the distance L2 between the second ironing ring 12 and the third ironing ring 13 is 23.
It was 0 mm. The approach angle α of the first ironing ring 11, the second ironing ring 12, and the third ironing ring 13 was 8 degrees.

Punch 10 used for ironing in the second step
0 body 10a (surface roughness is maximum height Ry = 0.26μ)
m) has an outer diameter of 65.95 mm, and the curvature 1 of the projection 10b.
The radius of curvature of 00b2 was 2.4 mm, and the height of the inner surface 10b3 from the ground contact portion was 28 mm. 4th ironing ring 54
Ironing portion 54b, ironing portion 5 of rear ironing ring 56
6b and the inside diameter of the ironing portion 57b of the front ironing ring 57 were 66.62 mm, 66.40 mm and 66.25 mm, respectively. The distance L4 between the fourth ironing ring 54 and the rear ironing ring 56 is 375 mm, the distance L5 between the rear ironing ring 56 and the front ironing ring 57 is 6 mm, and the distance L6 between the ironing part 56b and the ironing part 57b is It was 25 mm. The approach angle α of the fourth ironing ring 54 was 8 degrees, and the approach angle α of the rear ironing ring 56 and the front ironing ring 57 was 4 degrees. Rear ironing ring 56 and front ironing ring 57
The ironing rates at 32.8% and 33.3% respectively
Met.

The cooling lubricating liquid used in the ironing process was “J602A (product number: kinematic viscosity at 40 ° C .: 68 mm ² / sec) manufactured by Nippon Quaker Chemical Co., Ltd.”. Under the above conditions, the ironing process of the first step and the second step was performed. The height of the final ironing compact 28 pulled out from the punch 100 was about 370 mm. The portion of the final ironing compact 28 above the height of about 320 mm from the bottom was not subjected to ironing by the double ironing ring 55, and was trimmed at a height of 315mm by wire electric discharge machining. The bottom side was similarly trimmed to produce a thin cylinder 22 having a length of 295 mm. The average thickness of the thin cylindrical body 22 was 0.15 mm, and the uneven thickness (thickness variation) was 0.010 mm.

Under the above conditions, ten (No. 1 to 10) samples of the thin cylinder 22 were prepared. In the free state shown in FIG. 19, and at the two open ends shown in FIG.
In the state where the end body 60 with a (for mounting the thin-walled cylindrical body 22 on the shaft) is fitted (fitting depth d = 10 mm), the position A (27. 5mm
B) (position of 87.5 mm), C (position of 14)
Roundness was measured at 7.5 mm position, D (207.5 mm position) and E (267.5 mm position). As a measuring device, a non-contact type circularity cylindrical measuring device RL-101 manufactured by Mitutoyo Corporation was used. Table 1 shows the results. Further, the surface roughness of each sample was measured using a surface roughness shape measuring device 575A-3DF manufactured by Tokyo Seimitsu Co., Ltd., and the maximum height Ry was 1 μm or less for each sample.

[0047]

[Table 1]

In Table 1, the "maximum value" refers to the maximum roundness among the roundnesses of the positions A, B, C, D, and E of each sample, and the unit is mm. For example, in the free state of sample No. 1, the maximum roundness is obtained at the position E, which indicates that the value is 0.08 mm. Regarding “evaluation”, the maximum value of all 10 samples was 0.
A case of 10 mm or less was evaluated as ○, and even a single sample having a maximum value exceeding 0.10 mm was evaluated as ×.

Comparative Example 1: In the second step, the rear ironing ring 56 and the front ironing ring 5 of the double ironing ring 55
7 so that the distance L5 between them is 230 mm,
Ironing is performed in the same manner as in Example 1, except that the distance L4 between the fourth ironing ring 54 and the rear ironing ring 56 is set to 150 mm, to form a final ironing molded body 28, and similar to Example 1. And trimmed to produce a thin cylinder 22 having a length of 295 mm. The average thickness of the thin cylinder 22 was 0.15 mm, and the thickness deviation was 0.009 mm.

10 pieces (Nos. 11 to 2)
A sample of the thin cylinder 22 of 0) was prepared, and the roundness was measured. Table 2 shows the results. The variation in roundness was larger than in Example 1, and the evaluation was x. The surface roughness of each sample was measured using a surface roughness shape measuring device 575A-3DF manufactured by Tokyo Seimitsu Co., Ltd., and the maximum height Ry of each sample was 1 μm or less.

[0051]

[Table 2]

Example 2: Aluminum alloy plate having a thickness of 0.95 mm (JIS H 4000 alloy number 3004)
From H12), a blank having a diameter of 161 mm was punched out, the blank was drawn into a drawn body having an inner diameter of 87 mm, and then redrawn to an inner diameter of 66.1 mm. The hole is formed so that the center coincides with the axis, the open end is trimmed, and the shape is the same as that of the metal tube 1 having the inward flange portion 4 in FIG. A cylindrical element tube having a thickness of 0.95 mm was prepared. The thickness of the inward flange 4 was 0.95 mm, unchanged from the original thickness.

An ironing element 7 was formed from this cylindrical elemental tube using the tool shown in FIG. 3 by the method shown in FIG. The inner surface radius of curvature r1 of the curved portion 7b1 of the folded portion 7b was 2.7 mm, and the height h of the short cylindrical portion 7b2 was 5.0 mm (see FIG. 5). This ironed body 7 is formed into a final ironed compact 28 in the same manner as in Example 1 except that the third ironing ring 13 is not used in the first step, and both ends are trimmed to form a thin cylinder having a length of 295 mm. Body 22 was created. The average thickness of the thin-walled cylindrical body 22 is 0.15 mm, and the uneven thickness is 0.007.
mm.

In the same manner as in Example 1, 10 pieces (Nos.
30) A sample of the thin cylinder 22 was prepared, and the roundness was measured. Table 3 shows the results. The variation in the roundness was small, and was equivalent to that of the first embodiment. That is, the evaluation is ○
Met. The surface roughness of each sample was measured using a surface roughness shape measuring device 575A-3DF manufactured by Tokyo Seimitsu Co., Ltd., and the maximum height Ry of each sample was 1 μm or less.

[0055]

[Table 3]

Comparative Example 2: Instead of forming the folded portion 7b, an iron body obtained by forming a curled portion having a central angle of 90 degrees and an arc-shaped cross section whose end face extends substantially in the axial direction is used. Ironing was performed using the same materials and equipment as in Example 1 except for the differences. However, during the first ironing operation, the curl portion cannot withstand the load caused by the projections 10b of the punch 10 during the ironing operation, and the punch 10 protrudes from the ironing element body being ironed and cannot be formed, and the operation is interrupted. did.

[0057]

The invention according to claim 1 has the following effects. (A) Even when the thickness of the metal tube and the formed thin cylinder is thin, there is no risk of causing breakage of the tool or stopping production, and a relatively long thin cylinder is manufactured from the metal tube by the ironing method. be able to. (B) When the punch is extracted from the formed thin cylinder, there is no possibility that the vicinity of the opening will buckle, and a relatively long thin cylinder can be manufactured from the metal tube by ironing. (C) The roundness of a relatively long thin-walled cylinder manufactured by ironing from a metal tube is good in roundness, and the variation in roundness of each thin-walled cylinder is small. Furthermore, even after the end bodies are fitted into both open ends of the thin cylinder, the roundness of the thin cylinder is good, and the variation in the roundness of each thin cylinder is small. The invention according to claim 2 contributes to exhibiting the effects (a) and (b) of the invention according to claim 1 because the cross-section modulus of the folded portion is large. The invention according to claim 3 is:
Since the section modulus of the folded portion is larger than that of the invention according to the second aspect, (a) of the invention according to the first aspect,
It further contributes to the effect of (b).

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing an arrangement of an apparatus and a metal pipe before a first step of forming a folded portion in a cylindrical metal pipe in the present invention.

FIG. 2 is a longitudinal sectional view showing a state immediately after a first step is completed using the apparatus of FIG. 1;

FIG. 3 shows a second example in which a folded portion is formed in a cylindrical metal tube.
It is a principal part longitudinal cross-sectional view which shows arrangement | positioning of an apparatus and the metal element pipe which passed through a 1st process before a process start.

4 is a vertical sectional view showing a state immediately after a second step is completed and a folded portion is formed using the apparatus of FIG. 3;

FIG. 5 is a longitudinal sectional view of an ironing element having a folded portion formed in a second step.

FIG. 6 is an explanatory longitudinal sectional view showing a state immediately before ironing in a first step of performing ironing according to the present invention.

FIG. 7 is an explanatory longitudinal sectional view showing a state immediately before ironing in a second step of performing ironing according to the present invention.

FIG. 8 is an explanatory longitudinal sectional view showing a process of ironing with a double ironing ring in the present invention.

FIG. 9 is a longitudinal sectional view showing an example of a double ironing ring in a mode different from that of the double ironing ring shown in FIG. 8;

FIG. 10 is a vertical cross-sectional view showing a state at the time when the punch has risen very slightly from the bottom dead center and the folded portion and the stripper device have started to engage with each other in the present invention.

FIG. 11 is a transverse sectional view taken along the line XI-XI in FIG. 10;

FIG. 12 is an explanatory longitudinal sectional view showing a state in which ironing has been completed and the punch has approached the stripper device in the present invention.

FIG. 13 is an explanatory longitudinal sectional view showing a state where the punch has reached a bottom dead center in the present invention.

FIG. 14 is an explanatory longitudinal sectional view showing a state in which a punch has been extracted from an ironing formed body in the present invention.

FIG. 15 is a longitudinal sectional view of a thin cylinder formed by the method of the present invention.

FIG. 16 is an explanatory longitudinal sectional view showing a state immediately before a punch is extracted from an ironing compact by a conventional method.

FIG. 17 is a longitudinal sectional view showing an ironing punch of the present invention in a mode different from that of the ironing punch shown in FIG. 6, and an ironing formed body formed by using the ironing punch before the ironing punch is extracted.

18 is an explanatory longitudinal sectional view showing a state in which the ironing punch of the present invention in a further different form from the ironing punch shown in FIG. 6 is being extracted from the ironing molded body.

FIG. 19 is a longitudinal sectional view showing an example of a position for measuring roundness of a thin-walled cylindrical body manufactured by the method of the present invention.

FIG. 20 is a longitudinal sectional view showing an example of a position at which roundness is measured after the end bodies are fitted into both open ends of the thin-walled cylindrical body manufactured by the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal tube 7b Folding part 7b1 Curvature part (annular groove part) 7b2 Short cylindrical part (short cylindrical shape part) 7c Space part 10 Ironing punch (first ironing punch) 10b Projection part 21 Ironing molded body (intermediate ironing molded body) Reference Signs List 22 Thin cylindrical body 28 Ironing formed body (final ironing formed body) 55 Double ironing ring 56 Rear ironing ring 57 Front ironing ring 100 Ironing punch (second ironing punch)

Claims (3)

[Claims] 1. An annular shape is formed on the inner surface of one opening end of a cylindrical metal tube or on the inner surface of the opening of a cylindrical metal tube having an inward flange at one opening. A folded portion having a space portion is formed, and a hollow cylindrical projection of an ironing punch is inserted into the space portion, and is engaged with the folded portion to advance the ironing punch, and a front ironing ring and a rear ironing ring are formed. While ironing with the front ironing ring, only the double / ironing ring where the front ironing ring and the rear ironing ring are arranged so that ironing is performed with the rear ironing ring, or placed at the front end Ironing is performed in cooperation with a double ironing ring and one or more ironing rings to form an ironing compact, and an ironing punch is extracted from the ironing compact, and both ends of the ironing molding are trimmed. A method for manufacturing a thin-walled cylindrical body. 2. The method according to claim 1, wherein the folded portion comprises an annular groove. 3. The method according to claim 1, wherein the folded portion comprises an annular groove and a short cylindrical portion or a trapezoidal portion connected to the annular groove.