JPS6312692B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a tube of different diameters, which has a constant inner diameter and partially different outer diameters. The conventional manufacturing method for producing pipes 1 of different diameters as shown in Fig. 1, which have a constant inner diameter and partially different outer diameters, involves cutting the outer periphery of a pipe whose inner and outer diameters are uniform using a lathe or the like. Thin wall part 2 by drawing process
A method in which a plug and a pipe having a large diameter part and a small diameter part are integrally moved at a required interval and pulled out through a die, and then the plug is pulled out (Tokuko Shou 52 -471), a method of pulling the plug through a die while reciprocating the plug at any time (Japanese Patent Publication No. 52-5471), etc.
However, the material yield is poor, the length of the product is limited, the thick part of the product with a different diameter is only formed in one place, and the number of steps increases because the drawing direction is reversed. The dimensional accuracy of the product was poor, and the cold working rate of the thin-walled part and the thick-walled part of the product differed in the products, resulting in non-uniformity of the material inside the product with different diameters, all of which had problems. The present invention has good dimensional accuracy and high yield in one drawing process, and can form multiple thick parts as needed.Furthermore, by combining it with an annealing process, the material inside the product can be made uniform and different diameters can be formed. The purpose is to manufacture pipes. In the manufacturing method of the present invention, a tube is inserted between a slidable split-type two-stage die having a valley portion having the same shape and size as the thick wall portion of the finished tube of different diameters, and a plug having a parallel portion and a tapered portion at the rear. The pipe is drawn out by changing the positional relationship between each die of the two-stage die and the plug as appropriate. The method of the present invention will be explained below with reference to the drawings. FIG. 2 shows the state in which the original tube 14 is drawn out to produce the different diameter tube 1 by the method of the present invention. The front die 6 and the rear die 7 are secured by bolts 10 to form a split two-stage die, and the shape and dimensions of the die valley formed by the rear part of the front die 6 and the front part of the rear die 7 are The shape and dimensions match the thick wall portion of the different diameter tube 1. The two-stage die is held in the die stand 4, and is held at the front part of the die stand 4 (on the side of the die stand 12) by the distance piece 5.
A required distance d is maintained between the die stopper 9 provided at The distance d is made to match the length l of the thick wall portion of the finished pipe with different diameters shown in FIG. Plug 8
has a parallel part and a tapered part, and is inserted into the die hole and fixed at the rear by a plug rod 13. The distance pieces 5 are secured to the rear die 7 by bolts 11, and in this example, four pieces are used as shown in FIG. 3, and each can be removed from the die stand by removing the bolts 11. There is. The front die 6 is 2 as shown in FIG.
The bolt 10 is divided into parts as shown in Figure 2.
It is secured to the rear die 7 by a bolt, and can be removed from the die stand by removing the bolt 10 after removing the distance piece 5. When the distance piece 5 is set as shown in FIG. 2, the rear end of the bearing land 16 of the front die 6 is located on the parallel part of the plug 8.
The bearing land 17 of the rear die 7 is the plug 8
When the distance piece 5 is removed and both dies 6 and 7 move forward and stop in contact with the die stopper 9, at least the bearing land 17 of the rear die 7 is in contact with the plug 8.
is located on the parallel part of. The diameter of the front die bearing land 16 and the diameter of the rear die bearing land 17 shown in FIG. Match. Figure 4 shows the molding process. The dimensions of the raw tube 14 are appropriately selected depending on the processing rate required for the finished product.
The inner diameter shall be larger than the finished product inner diameter. When molding,
First, as shown in FIG. 4a, the original tube 14 is set on a draw bench. At this time, one end of the raw tube 14 is passed through the rear die 7 and the front die 6 from the right side of the figure, but the diameter is previously reduced to the required length using a processing machine such as a rotary swager (not shown). Further, a mouth portion 15 is formed at the tip of the original tube 14 by the processing machine or the like so that it can be gripped by the jaw 12. As shown in Fig. 4a, pass one end of the raw tube 14 through the die hole, grip the mouth part 15 with the jaw 12, insert the plug 8 into the raw tube 14 from the rear, and fix the rear end of the plug rod 13. Leave it free. When the jaw 12 is pulled forward in this state, both the original tube 14 and the plug 8 enter the die hole, and the state shown in FIG. Back of the end (right side in Figure 4)
The position of the plug 8 is fixed by fixing the rear end of the plug rod 13 in the most recent state. At this time, the tube between the tip of the plug 8 and the front die bearing land 16 is formed as a thin wall portion 2 of a finished tube with different diameters. Next, the front thin wall portion of the finished pipe with different diameters is formed.
From the state shown in Fig. 4b to the state shown in Fig. 4c, Joe 1
When you pull 2 forward, the original tube 14 first moves backward to the die 7.
The outer diameter side is pressed down and the entire wall thickness deforms toward the tube axis, and then the plug taper part
0, the inner diameter side is expanded and the outer diameter side is slightly raised in the die valley 18, and then the outer diameter side and the inner diameter side are rolled down by the front die 6 and the plug parallel part 19, resulting in a thin walled product with different diameters. Part 2 is molded. FIG. 4c shows the point in time when the thin-walled portion 2 has been formed to the required length, and the jaw 12 is stopped in this state. Next, the thick-walled portion of the finished pipe with different diameters is formed. First, the distance piece 5 is removed as shown in FIG. 4c. This removal is carried out by removing the bolt 11 shown in FIGS. 2 and 3, although it is not shown in the same figure. Next, when the jaw 12 is pulled forward, the deformed tube between the front die 6 and the rear die 7 is expanded along the plug taper portion 20, and the die valley portion 18 is expanded as shown in FIG. 4d.
Push the front die 6 from behind while filling the inside,
Further, the raw tube 14 pushes the rear die 7 from behind, and the front die 6 and the rear die 7 slide on the inner surface of the die stand 4 and move forward. At this time, the tube filled in the die valley 18 by the plug 8 becomes the thick wall portion 3 of the finished tube with different diameters. In FIG. 4d, there is still a blank space in the die valley 18. As shown in Figure 4e, the rear die bearing land 17 is connected to the parallel part 19 of the plug.
When it comes to the top, the die valley 18 is completely filled,
The thick wall portion 3 of the finished product with different diameters is completed. At this time, the front die 6 and the rear die 7 come into contact with the die stopper 9 and stop the jaw 12 at the same time. Next, the rear thin-walled portion of the finished pipe with different diameters is formed.
First, when the bolt 10 is removed in the state shown in FIG. 4e, and then the jaw 12 is pulled forward, the original tube 14 is formed by the rear die 7 and the plug 8 and has a thin rear wall, as shown in FIG. 4f. 2', and the already formed thick part 3 pushes the front die 6 out of the die stand 4. Since the extruded front die 6 is divided, it can be easily removed from the finished product different diameter tube 1 as shown in FIG. 4g. Further, the jaw 12 is pulled forward to pull out the original tube 14 between the rear die 7 and the plug 8, and the forming of the different diameter tube 1 is completed. In addition, when molding a tube with different diameters having multiple thick-walled parts 3, the rear thin-walled part 2' is formed as shown in Fig. 4g.
After forming a length shorter than the required length of the intermediate thin section by the length of the die trough, as shown in FIG.
Attach to. Next, the rear end of the plug rod 13 is unfixed, the jaw 12 is moved rearward, and the tube, front die 6, rear die 7, and plug 8 are integrally moved rearward inside the die stand 4 as shown in Fig. 5b. Attach distance piece 5.
Next, pull the jyo 12 forward and pull out the plug 8 together with the original tube 14 as shown in Fig. 5c, and when the positional relationship between the plug 8 and the front die 6 becomes as shown in Fig. 4b, the jyo 12 is pulled out. Stop and fix the rear end of the plug rod 13. Next, remove the distance piece 5 and pull the Jyo 12 forward. Then, the thick-walled portion 3 of the finished tube with different diameters is formed in the same manner as shown in FIG. 4d. Thereafter, the rear thin wall portion is formed in the same manner as in FIG. 4 e, f, and g. In this way, Figure 4 a~
Following each step in f, Fig. 5 a to c, Fig. 4 d to f
By repeating each step, a pipe of different diameters having a plurality of thick-walled parts can be manufactured. If the thick wall part of the finished pipe with different diameters is long, the die valley must be made wider and the drawing distance from c to e in Figure 4 must be made longer. In this case, the distance piece 5 can be made thicker, but if the increased weight makes installation and removal difficult, the distance piece 5 can be made thicker.
As shown in the figure, a notch 21 is provided at the tip of the rear die 7 on the side of the die stand 4 so that the distance d between the die stopper 9 and the rear die 7 is equal to the length of the thick part (including the tapered part). Bye. The different diameter tubes manufactured as described above have different mechanical properties such as hardness because the processing rate is different between the thin and thick parts, which may cause problems depending on the application. In such a case, the material can be made uniform in the following manner using the method of the present invention. That is, first, an intermediate variable diameter tube having a diameter larger than that of the finished variable diameter tube, a thin wall portion, and a thick wall portion is drawn from the original tube having a uniform wall thickness as shown in FIG. 4, and then this is annealed. Furthermore, the annealed intermediate tube with different diameters is used as a master tube and is pulled out as shown in FIG. At this time,
The thin-walled portion and thick-walled portion of the intermediate different-diameter tube are used as the thin-walled portion and thick-walled portion of the finished different-diameter tube, respectively, and the inner diameter and thin-walled portion of the intermediate different-diameter tube are , determine the size of the thick part. Note that if the intermediate pipe with different diameters is drawn in two or three stages, the material of each part of the finished pipe with different diameters will be made more homogeneous. Examples Different diameter tubes having an inner diameter of 40.6 mm, a wall thickness of the thin wall portion of 1.2 mm, and a wall thickness of the thick wall portion of 2.0 mm were manufactured using the methods shown in Table 1 using ausnitic stainless steel tubes as original tubes. Incidentally, Table 1 C (conventional method) is a product manufactured by a conventional method known from Japanese Patent Publication No. 52-471.

[Table] Figure 7 shows the longitudinal distribution of hardness at the center of the cross-sectional wall thickness of the manufactured product with different diameters. As is clear from the figure, according to the method of the present invention, the difference in hardness between the thin-walled part and the thick-walled part is small, and in particular, A, which was drawn in three stages, has almost uniform hardness in the length direction. It is being In addition, in the method A of the present invention, the thin part on the left side is the front thin part, and in the method B of the present invention, the thin part on the right side is the thin part at the front.
In A and B, the reason why the front thin wall part is slightly higher in hardness than the rear thin wall part is because the front thin wall part is emptied by the rear die and becomes a small diameter tube, as shown in Figure 4b. be. However, such a small difference in hardness does not pose a practical problem. As described above, according to the method of the present invention, different diameter tubes with a constant inner diameter and partially different outer diameters can be formed with good yield and dimensional accuracy, and if necessary, different diameter tubes with multiple thick-walled parts can also be formed. Furthermore, by performing drawing in two or three stages, the difference in mechanical properties between the thin-walled portion and the thick-walled portion can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a tube of different diameter formed by the method of the present invention, FIGS. 2, 3, and 6 are diagrams showing examples of an apparatus for carrying out the method of the present invention, and FIGS. The drawings are diagrams showing each molding step of the method of the present invention, and FIG. 7 is a diagram showing the hardness distribution of the example. 1: Different diameter pipe, 2: Thin wall part of different diameter pipe, 3: Thick wall part of different diameter pipe, 4: Die stand, 5: Distance piece, 6: Front die, 7: Back die, 8: Plug, 9: Daistopper, 10: Bolt, 11:
Bolt, 12: Jiyo, 13: Plug rod, 1
4: Original pipe, 15: Mouth part, 16: Front die bearing land, 17: Back die bearing land, 18: Die valley, 19: Plug parallel part,
20: Plug taper part, 21: Rear die tip notch.

Claims (1)

[Scope of Claims] 1. In the production of different diameter tubes with a constant inner diameter and partially different outer diameters, a slidable split-type two-stage structure having a trough portion having the same shape and size as the thick wall portion of the different diameter tube. A tube is passed between the die and a plug having a parallel portion and a tapered portion at the rear, and (a) a front thin-walled portion forming process in which the inside of the tube is rolled down by the front die of the two-stage die and the parallel portion of the plug; (b) the two-stage die A thick-walled part forming process in which the tube is filled in the valley part of the die while sliding the die.C) The two-stage die is divided into a front die and a rear die, and the rear die is compressed by the parallel part of the rear die and the plug. A method for manufacturing a pipe of different diameters, characterized by sequentially performing thin-walled portion forming steps. 2. After forming the rear thin-walled part, the die is changed to a two-stage die, and a thick-walled part forming process is performed in which the valley part of the die is filled with pipe wall while sliding the two-stage die, and then the two-stage die is replaced with the front die and Claim 1, characterized in that the tube is divided into rear dies, and a thin-walled section forming process is performed in which the tube wall is rolled down by the parallel portions of the rear dies and the plug, to produce a tube of different diameters having a plurality of thick-walled sections. 2. Method for manufacturing pipes with different diameters as described in Section 1. 3. A front thin-walled part forming process is performed on the thin-walled part of the cold-formed and annealed different-diameter pipe, a thick-walled part-formed process is performed on the thick-walled part of the different-diameter pipe, and the other parts of the different-diameter pipe are subjected to a thin-walled part forming process. 3. The method for manufacturing a different diameter tube according to claim 1 or 2, characterized in that a rear thin-walled portion forming step is performed on the thin-walled portion of the tube.