JPH07136710A - Method and device for manufacturing tube by hot extrusion - Google Patents

Abstract

PURPOSE:To manufacture a tube with less uneven thickness and a high quality with a hollow billet centered satisfactorily by inserting the tip part of the hollow billet into a parallel part with a diameter smaller than a container hole. CONSTITUTION:When a seamless metallic tube is manufactured by a hot extrusion tube manufacturing method, using a hollow billet 10 with the same outside diameter in its axial direction, after obtaining a state in which a difference in diameter between the outside diameter Db of an insertion billet in the extrusion tip part of the hollow billet 10 in a container 3 with the same standard inside diameter Dc in its axial direction and the inside diameter Dh of a parallel part 9 restricting the tip part of the billet 10, satisfies 0.5mm<=Dh-Db<=0.025 Dcmm and Dc-Dh>0, the hollow billet billet when the billet is heated at an extrusion temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot extrusion pipe manufacturing method and a pipe manufacturing apparatus therefor.

[0002]

2. Description of the Related Art As a tube manufacturing technique, a method of extruding a heated hollow billet is known. Fig. 5 shows the conventional Ugine Sejour.
FIG. 2 is a principle diagram of a hot extrusion pipe manufacturing apparatus according to the method of FIG. 1), in which the hot extrusion pipe manufacturing apparatus 100 includes a container 102 having a container hole 101, a die holder 103 attached to an outlet of the container hole 101, The die holder 103 comprises a die 104 that is accurately fitted to the die holder 103, a stem 105 that slides in the container hole 101, and a mandrel 106 that defines the inner diameter of the tube. The die holder 103 has an outer peripheral surface which is an annular convex surface 103a.
Is brought into contact with the conical receiving surface 101a at the outlet of the container hole 101 to position it. Further, since the die 104 receives an extremely large pushing force, the die backer 107 receives the back surface.

Next, the operation will be described. Container hole 101
A glass disk 108 where glass powder is hardened is placed in the inner part of the container (the front surface of the die holder 103), and a hollow billet 110 that is sufficiently red-heated is placed in the container hole 101.
(The surface of the billet 110 is covered with glass powder.) Is inserted, the mandrel 106 is passed through the center, and the stem 105 is strongly extruded through the dummy block 111.

Then, the hollow billet 110 is formed by the die 10.
The outer diameter is regulated by squeezing with 4, and the inner diameter is adjusted to the mandrel 106
And the desired tube 112 is formed. The mandrel 106 advances with the stem 105.

At this time, the glass powder applied to the outer circumference of the hollow billet 110 is the hollow billet 110 and the container hole 10.
1 and the glass disk 108 is a lubricant between the die 104 and the outer circumference of the tube 112 while melting. To explain the glass lubrication, in the hot extrusion in which the hollow billet 110 is heated by red heat, if the glass powder is not present, the die 10 made of tool steel or the like is used.
No. 4, the surface hardness quickly halved, and could not be put to practical use. Grease / graphite mixed lubricant used in low-temperature extrusion cannot be used because it burns. Therefore, the Eugene-Sejournet method employs glass powder (fiber) as a lubricant, and this glass powder (fiber) also has a high heat insulating property and also serves to suppress the temperature rise of the die 104 and the container 102.

[0006]

FIG. 6 is an enlarged view of the tip portion of a tube manufactured by the prior art, in which the tube 112 tends to have an uneven thickness, that is, a non-uniform wall thickness, and in particular, the tip is " There is a marked tendency to have uneven thickness like "Bamboo spear". It is considered that the cause is that the deformation resistance varies due to the nonuniform temperature of the hollow billet, or the hollow billet is deformed unevenly due to the gap between the hollow billet and the tool holding the hollow billet.

As one of the measures against the uneven thickness, Japanese Patent Publication No. 59-420.
There is a "Method for controlling wall thickness of extruded hollow metal product" in Japanese Patent No. 6, which uses an extrusion die 6 (die holder 1 in FIG. 5).
(Corresponding to 03) and another centering die 4 are prepared. First, the mandrel 3 is centered by the centering die 4, and the ram 5 is advanced by a certain distance to plastically deform the billet 2. Closely contact the mandrel 3. Next, the centering die 4 is removed, the extrusion die 6 is attached, and the ram 5 is advanced to extrude the pipe.

Although this improved method has the effect of correcting uneven thickness,
A new process consisting of preparing the centering die 4, stopping the ram 5 once, and replacing the centering die 4 with the extrusion die 6 is added to the conventional method, resulting in a long production time. However, there are inconveniences such as difficulty in control and increase in equipment cost. Therefore, an object of the present invention is to provide a hot-extrusion pipe manufacturing method and a device therefor, which have good processing accuracy in the same steps as conventional ones.

[0009]

Means and Actions for Solving the Problems In order to achieve the above object, the method of the present invention is to produce a seamless metal pipe by a hot extrusion pipe making method using a hollow billet having the same outer diameter in the axial direction, The diameter difference between the insert billet outer diameter Db at the extruding tip portion of the hollow billet and the tool inner diameter Dh of the portion that restrains the tip portion of the billet in the container having the same reference inner diameter Dc in the axial direction is expressed by the following formula ( It is characterized by extruding after the condition 1) and the formula (2) are satisfied. 0.5 mm ≤ Dh-Db ≤ 0.025 Dc mm (Equation (1) Dc-Dh> 0 (Equation (2)) where Db: Billet outer diameter (mm) when heated to extrusion temperature

In the apparatus according to the present invention for carrying out the method of the present invention, a parallel portion having the same inner diameter Dh in the axial direction, which satisfies the conditions of the following formulas (1) and (2), is provided at the center of the inlet end face. The formed die holder has the same reference inner diameter D in the axial direction.
It is characterized in that the parallel portion is connected so as to face the output side end having c. 0.5 mm ≤ Dh-Db ≤ 0.025 Dc mm (Equation (1) Dc-Dh> 0 (Equation (2)) where Db: Billet outer diameter (mm) when heated to extrusion temperature

Alternatively, the apparatus according to the present invention for carrying out the method of the present invention has the same reference inner diameter Dc in the axial direction and satisfies the conditions of the following equations (1) and (2) at the exit end thereof. The inlet side end surface of the die holder in which an annular convex surface having a top diameter substantially matching the inside diameter Dh is formed on the inlet side end surface at the outlet side end of the container in which the parallel portion having the same inner diameter Dh in the axial direction is formed. Are opposed to each other and connected. 0.5 mm ≤ Dh-Db ≤ 0.025 Dc mm (Equation (1) Dc-Dh> 0 (Equation (2)) where Db: Billet outer diameter (mm) when heated to extrusion temperature

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a first embodiment of a hot extrusion pipe forming apparatus according to the present invention. A hot extrusion pipe forming apparatus 1 comprises a container 3 having a container hole 2 having the same reference inner diameter Dc in the axial direction. , Die holder 4 attached to the outlet of container hole 2
And the die 5 accurately fitted to the die holder 4,
It consists of a stem 6 that slides in the container hole 2 and a mandrel 7 that moves with the stem 6. The die holder 4 is, as it were, a die holder with a neck, and a neck portion 8 thereof.
Is provided with a parallel portion 9 having an inner diameter Dh and a length L. This parallel portion 9 is the extruding tip portion 10 of the hollow billet 10.
It becomes a tool portion for restraining a (hereinafter, abbreviated as "tip portion 10a").

Hollow billet 1 having the same outer diameter Db in the axial direction
0, the container hole 2 having the reference inner diameter Dc, and the diameter D of the parallel portion 9
The relationship with h will be described below. First, Dh is set smaller than Dc. That is, Dc-Dh> 0. Also, D
h-Db is 0.5 mm or more and preferably 0.025 x Dc or less. That is, 0.5 mm ≦ Dh
It is -Db <= 0.025Dc. Dh-Db is 0.5
If the thickness is less than mm, the hollow billet 10 will be seized on the parallel portion 9, and if Dh-Db exceeds 0.025 × Dc, the uneven thickness exceeds the allowable value. The relationship shown above is a relationship first found by the present inventor from numerous experimental results. The billet outer diameter is the outer diameter under the condition of being heated to a predetermined extrusion temperature, and the standard inner diameter Dc of the container and the parallel portion 9 The inner diameter Dh of each is an inner diameter under normal temperature conditions.

Next, the length L of the parallel portion 9 and the taper angle θ of the guide portion 11 at the tip of the parallel portion 9 will be described. The length L of the parallel portion 9 must be greater than the sum of the length d of the glass disk 12 involved in L and the radius R of the outer peripheral tip of the hollow billet 10. If the effective length is Leff (not shown), it can be expressed as Leff = Ld-R> 0. However, this Leff cannot be made too large, and is 1/6 of the total length (maximum) of the hollow billet 10 to be handled, preferably 1/2.
It is 0 to 1/10. For example, if the total length of the hollow billet 10 is 613 mm, the limit value of Leff is 100 mm. If it exceeds this, the glass powder applied to the outer peripheral surface of the billet is scraped off by friction with the parallel portion 9, and seizure is likely to occur in the parallel portion 9. Further, the taper angle θ of the guide portion 11 is important, and the taper angle θ is preferably a gentle slope of 30 ° or less with respect to the longitudinal axis. Alternatively, a rounded guide portion is desirable. All of these are for suppressing / preventing the occurrence of image sticking in the parallel portion 9.

In the die holder 4, the outer peripheral surface of the neck portion 8 is a tapered conical surface 13, and a concave portion 14 is formed at the exit side end of the container 3 corresponding to the conical surface 13. Therefore, the parallel portion 9 having the same inner diameter Dh in the axial direction
The die holder 4 formed at the center of the inlet side end face is connected to the outlet side end of the container 3 having the same reference inner diameter Dc in the axial direction with the parallel portion 9 opposed.

The operation of the hot-extrusion pipe forming apparatus having the above structure will be described below. FIG. 2 is a diagram for explaining the initial operation of the hot extrusion pipe manufacturing apparatus according to the present invention. A glass disk 12 where glass powder has been hardened is placed inside the container hole 2 (in front of the die holder 4) and the container hole is formed. 2. A hollow billet 10 (covering the surface with glass powder) that has been sufficiently heated in red heat is inserted into No. 2. The hollow billet 10 is centered by inserting the tip portion 10 a into the parallel portion 9 of the die holder 4. Subsequently, the mandrel 7 is passed through the center, and the hollow billet 10 is strongly extruded by the stem 6 via the dummy block 15.

FIG. 3 is a diagram for explaining an intermediate operation of the hot extrusion pipe manufacturing apparatus according to the present invention. The well-centered hollow billet 10 is squeezed by a die 5 to define the outer diameter and the inner diameter of the mandrel 7. And the desired tube 16 is formed. The mandrel 7 advances with the stem 6.

Next, an experimental example using the device 1 of the present invention will be specifically described. Hollow billet is made of material: JIS-SUS30
4. Heating temperature: 1200 ° C, dimensions in this state are outer diameter Db: 174.8 mm, inner diameter: 41.9 mm, length: 6
13 mm, tip end R: 15.3 mm, and the number of samples per test number: 10. Inner diameter of die 5: 4
6.6 mm, outer diameter of mandrel 7: 38 mm, diameter of container hole 2 Dc: 181 mm, dimension d of glass disk 12: 20 mm, length L of parallel portion 9: 70 mm, taper angle θ: 10 °.

From the above conditions, Dh of the device of the present invention is calculated as follows. Formula (1): 175.3 ≦ Dh ≦ 179.3 However, the calculation formula is 0.5 mm ≦ Dh−Db ≦ 0.025D
Db + 0.5 mm ≦ when c is deformed with respect to Dh
Dh ≦ Db + 0.025Dc. Formula (2): Dh <181 However, the calculation formula is a modified formula Dh <Dc of Dc-Dh> 0. Within and outside the range of these conditions, pipes were manufactured with the extrusion pipe manufacturing apparatus 1 of FIG. 1 (first embodiment), and the presence or absence of seizure on the outer surface of the obtained pipe and the uneven wall thickness ratio at the pipe tip 5 m were measured. Examined.
The results are shown in Table 1.

[0020]

[Table 1]

Test No. 1 was determined by the first embodiment apparatus of FIG. 1 to set the diameter Dh of the parallel portion 9 to a value satisfying the expressions (1) and (2). Test Nos. 2 and 3 were determined by the apparatus of the first embodiment of FIG. 1 so that Dh was set to a value satisfying only Expression (2) but not Expression (1). Test No. 4 was determined to be a value in which Dh was unsatisfactory in both formulas (1) and (2) in the first embodiment device of FIG. Test No. 5 was tested using the conventional device shown in FIG.

"Surface condition" in the result column was visually determined, and "O" indicates that no seizure was observed, and "X" indicates that seizure was observed. In addition, the "uneven thickness ratio" in the column of results is obtained by cutting off the tip portion 15 mm of the obtained pipe, measuring the wall thickness with an ultrasonic wall thickness measuring device at the new tip portion 5 m, and calculating the following formula {( Maximum thickness-minimum wall thickness) / average wall thickness} to obtain the uneven thickness ratio (%) for each sample, and average the uneven thickness ratios in 10 samples. This average value (%) is 10% or less. If it was over 10%, it was evaluated as x. When the surface condition and the uneven thickness ratio both have a circle, the circle is described in the evaluation column. Only the test number 1 was evaluated as ◯, and it was found that a good pipe can be manufactured by the device 1 of the present invention according to the formulas (1) and (2).

FIG. 4 is a view of a second embodiment of the hot extrusion pipe forming apparatus of the present invention. The hot extrusion pipe forming apparatus 21 has a parallel portion 22 for holding the tip portion 10a of the billet 10 in the container 2
3 is provided. Since the container 23 and the die holder 24 are different from the container 3 and the die holder 4 of the first embodiment, these will be described. Since the other dies 5, the stem 6 and the mandrel 7 are not changed, the reference numerals are used and the detailed description is omitted.

A container hole 25 having an inner diameter Dc is formed in the container 23, and an inner diameter D is formed at the outlet of the container hole 25.
A parallel portion 22 having a length L is formed by h. The guide portion 26 smoothly reduces the diameter from the container hole 25 to the parallel portion 22.

The die holder 24 has an annular convex surface 24a formed on the front end side of the entrance side, and the top 24b of the annular convex surface 24a.
Is substantially the same as the inner diameter Dh of the parallel portion 22.
On the other hand, a conical receiving surface 22a corresponding to the annular convex surface 24a is formed at the exit end of the container 23. Therefore,
A container having the same reference inner diameter Dc in the axial direction and the parallel portion 22 having the same inner diameter Dh in the axial direction which satisfies the conditions of the following formulas (1) and (2) at the exit end thereof. At the exit end of 23, a top portion 24 that substantially matches the inner diameter Dh
The hot extrusion pipe forming apparatus 21 for carrying out the method of the present invention can be constructed by connecting the inlet side end surfaces of the die holder 24, which has the annular convex surface 24a having b, formed on the inlet side end surfaces so as to face each other. 0.5 mm ≤ Dh-Db ≤ 0.025 Dc mm (Equation (1) Dc-Dh> 0 (Equation (2)) where Db: Billet outer diameter (mm) when heated to extrusion temperature

Next, an experimental example using the device 21 of the present invention will be specifically described. Hollow billet is made of material: JIS-SUS3
04, heating temperature: 1200 ° C., dimensions in this state are outer diameter Db: 174.8 mm, inner diameter: 41.9 mm, length:
613 mm, tip end R: 15.3 mm, and the number of samples per test number: 10. Inner diameter of die 5: 4
6.6 mm, outer diameter of mandrel 7: 38 mm, diameter Dc of container hole 25: value shown in Table 2, glass disk 12 involved dimension d: 20 mm, parallel portion 9 length L: 70 mm,
The taper angle θ is 10 °. Within and outside the range of these conditions, pipes were manufactured by the extrusion pipe manufacturing apparatus 21 of FIG. 4 (second embodiment), and the presence or absence of seizure on the outer surface of the obtained pipe and the uneven wall thickness ratio at the pipe tip 5 m were measured. Examined. The results are shown in Table 2.

[0027]

[Table 2]

Test No. 1 was determined by the apparatus of the second embodiment shown in FIG. 4 so that the diameter Dh of the parallel portion 22 was a value satisfying the expressions (1) and (2). Test Nos. 2 and 3 were determined by the apparatus of the second embodiment of FIG. 4 so that Dh was set to a value satisfying only Expression (2) but not Expression (1). Test No. 4 was determined to be a value where Dh was unsatisfactory in both formulas (1) and (2) in the apparatus of the second embodiment of FIG. Test No. 5 was tested using the conventional device shown in FIG.

"Surface condition" in the results column was judged by visual inspection. O indicates that no seizure was observed, and X indicates that seizure was observed. In addition, the "uneven thickness ratio" in the column of results is obtained by cutting off the tip portion 15 mm of the obtained pipe, measuring the wall thickness with an ultrasonic wall thickness measuring device at the new tip portion 5 m, and calculating the following formula {( Maximum thickness-minimum wall thickness) / average wall thickness} to obtain the uneven thickness ratio (%) for each sample, and average the uneven thickness ratios in 10 samples. This average value (%) is 10% or less. If it was over 10%, it was evaluated as x. When the surface condition and the uneven thickness ratio both have a circle, the circle is described in the evaluation column. Only the test number 1 was evaluated as ◯, and it was found that a good pipe can be manufactured by the device 21 of the present invention according to the formulas (1) and (2). That is, when the extrusion test was conducted using the apparatus 21 of the second embodiment, the same results as in Table 1 above were obtained. Therefore, it was confirmed that a good tube can be manufactured also in the device 21 of the second embodiment.

[0030]

As described above, according to the method of the present invention, when a seamless metal pipe is manufactured by a hot extrusion pipe manufacturing method using hollow billets having the same outer diameter in the axial direction, the same reference inner diameter is used in the axial direction. The diameter difference between the insert billet outer diameter Db at the extruded tip portion of the hollow billet in the container having Dc and the tool inner diameter Dh of the portion that restrains the billet tip portion is expressed by the following equations (1) and (2). ) Is satisfied and then extruded. 0.5 mm ≤ Dh-Db ≤ 0.025 Dc mm (Equation (1) Dc-Dh> 0 (Equation (2)) where Db: Billet outer diameter (mm) when heated to extrusion temperature By the above method, that is, by inserting the tip of the hollow billet into the parallel portion having a smaller diameter than the container hole, the hollow billet is well centered and a high-quality pipe with less uneven thickness can be manufactured.

In the extrusion pipe making apparatus for carrying out the method of the present invention, when the parallel portion is formed in the die holder, the container may be the same as the conventional one, and the die boulder may be exchanged. The device is not expensive. Further, when the parallel portion is formed in the container, the die holder can use the conventional product as it is.

[Brief description of drawings]

FIG. 1 is a diagram of a first embodiment of a hot extrusion pipe manufacturing apparatus of the present invention.

FIG. 2 is an explanatory diagram of initial operation of the hot extrusion pipe manufacturing apparatus according to the present invention.

FIG. 3 is a diagram for explaining an intermediate operation of the hot extrusion pipe manufacturing apparatus according to the present invention.

FIG. 4 is a diagram of a second embodiment of the hot extrusion pipe manufacturing apparatus of the present invention.

FIG. 5: Principle diagram of a conventional hot-extrusion pipe manufacturing apparatus according to the Eugene-Sejournet method

FIG. 6 is an enlarged view of a tip portion of a tube manufactured by a conventional technique.

[Explanation of symbols]

1, 21 ... Hot extrusion pipe forming apparatus, 2, 25 ... Container hole,
3, 23 ... Container, 4, 24 ... Die holder, 5 ... Die, 6 ... Stem, 7 ... Mandrel, 9, 22 ... Parallel part,
10 ... Hollow billet, 10a ... Hollow billet tip (extrusion tip), 16 ... Pipe (seamless metal pipe), 24a ...
The annular convex surface of the die holder, 24b ... The top of the annular convex surface.

Claims (3)

[Claims] 1. When producing a seamless metal pipe by a hot extrusion pipe forming method using a hollow billet having the same outer diameter in the axial direction, the hollow billet in the container having the same reference inner diameter Dc in the axial direction is produced. Extrusion is performed after the diameter difference between the insertion billet outer diameter Db at the extrusion tip portion and the tool inner diameter Dh at the portion that constrains the tip portion of the billet satisfies the following equations (1) and (2). A hot extrusion tube manufacturing method characterized by the above. 0.5 mm ≤ Dh-Db ≤ 0.025 Dc mm (Equation (1) Dc-Dh> 0 (Equation (2)) where Db: Billet outer diameter (mm) when heated to extrusion temperature 2. A die holder in which a parallel portion having the same inner diameter Dh in the axial direction and satisfying the conditions of the following equations (1) and (2) is formed in the central portion of the inlet side end face is the same in the axial direction. The hot extrusion pipe forming apparatus for carrying out the method according to claim 1, wherein the parallel portion is connected to the outlet end of a container having a reference inner diameter Dc so as to face each other. 0.5 mm ≤ Dh-Db ≤ 0.025 Dc mm (Equation (1) Dc-Dh> 0 (Equation (2)) where Db: Billet outer diameter (mm) when heated to extrusion temperature 3. A parallel portion having the same reference inner diameter Dc in the axial direction and having the same inner diameter Dh in the axial direction satisfying the conditions of the following formulas (1) and (2) at the exit end thereof. An annular convex surface having a top diameter substantially matching the inner diameter Dh is connected to the exit end of the formed container so as to face the entrance end surface of the die holder formed on the entrance end surface. A hot-extrusion pipe forming apparatus for carrying out the method according to Item 1. 0.5 mm ≤ Dh-Db ≤ 0.025 Dc mm (Equation (1) Dc-Dh> 0 (Equation (2)) where Db: Billet outer diameter (mm) when heated to extrusion temperature