JPH0839107A - Metallic tube with relief pattern on inside surface, manufacture thereof and mandrel for manufacturing the tube - Google Patents

Abstract

PURPOSE:To provide a metallic tube with a relief pattern on the inside surface having the relief pattern on the whole inside surface of the long size metallic tube or the metallic tube having a thin inside diameter, method for manufacturing the metallic tube with the relief pattern on the inside surface and mandrel of a cold Pilger mill used in the manufacturing method. CONSTITUTION:By using the mandrel 5 having an ellipse-like recess 15 in the final stage region 8 of diameter reduction working part in the diameter reduction working part 6 of the mandrel of the cold Pilger mill, the diameter reduction and thinning work of the metal tube is executed with the cold Pilger mill and simultaneously the tube is manufactured by working the relief pattern 19 on the inside surface of the metallic tube. The relief pattern is worked on the inside surface of the metallic tube simultaneously with the diameter reduction and thinning work of the metal tube, so a special device is not necessary and the work of the relief pattern on the inside surface of the metal tube having a thin diameter and long size is executed at low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal pipe for use as an air transport pipe for transporting pellets such as plastic pellets, chips, granules, or flakes. The present invention relates to a metal tube with a floating pattern and a manufacturing method thereof.

[0002]

2. Description of the Prior Art Pellet, chips, granules, or plastic particles such as flakes transported by an air transportation pipe or the like are rubbed against the inner wall of the pipe during the air transportation and grow as a thin film. If the wall has appropriate irregularities, it has the effect of suppressing these growths and of quickly peeling off well, and conventionally, those having fine indentation patterns have been generally used.

However, a metal pipe having an indented pattern on its inner surface has a transport substance adhering to the indentation and enters, and it is difficult to remove the transport substance entering the indent. Therefore, it is time-consuming to clean and remove the transport substance when changing the transport substance. It takes. In addition, there is a drawback that productivity is remarkably poor, especially in the case of multi-type small lot production. On the other hand, the floating material with the protruding pattern does not enter the transport material and therefore does not take time to clean and remove it when changing the transportation material. Although it is convenient as the surface shape of the inner surface of No. 3, it is difficult to manufacture a metal tube with an inner surface floating pattern, and at least none of the steel tube has an inner surface with a floating pattern.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above problems, facilitates cleaning of the inner surface of a metal tube, and has an inner surface floater having a floating pattern on the entire inner surface of a long metal tube or a metal tube having a small inner diameter. The object is to provide a patterned metal tube, a method for manufacturing a metal tube with an inner surface floating pattern, and a mandrel of a cold pilger mill used for the manufacturing method.

[0005]

Means for Solving the Problems According to the invention of claim 1, the means for solving the above-mentioned problems is a float formed on the entire inner surface of a metal pipe by a diameter reduction and a thin-wall processing by a cold pilger mill. It is a metal tube with an inner surface floating pattern characterized by having a pattern.

According to the second aspect of the present invention, the mandrel of the cold-pilger mill has a mandrel having a recessed pattern on the entire circumference of the final stage area of the diameter-reducing portion of the mandrel. A method of manufacturing a metal pipe with an inner surface floating pattern, characterized by forming a thin wall and forming a floating pattern on the inner surface of the metal tube at the same time.

According to a third aspect of the present invention, a cold pilger for producing a metal pipe with an inner surface relief pattern is characterized in that a concave pattern is provided on the entire circumference of the final stage region of the diameter reducing action portion of the mandrel of the cold pilger mill. It is the mandrel of the mill.

[0008]

[Operation] Cold Pilger mill, as shown in Fig. 1,
A semi-circular cross section, and a reduced diameter portion 2 made of a reduced diameter caliber that continuously shrinks, and a sizing portion 3 made of a finished size caliber that is continuous with the reduced diameter portion 2 and does not change the cross section on the outer periphery, With the pinion gear 22 attached to the roll die shaft 4 and the fixed rack gear 21, the upper and lower two roll dies 1 that move forward and backward and roll, and the mandrel 5 whose cross section narrows toward the tip end of the material pipe 9 Is cold drawn to obtain the product pipe 11 through the reduced diameter pipe portion 10. The cross-sectional areas of the material pipe 9 and the product pipe 11 are about one-third the average on average, and the length is about three times the average.

In the companding, the roll die 1 is reciprocated once to compand the material tube 9, and then the material tube 9 is rotated together with the mandrel 5 by about 60 °. At the same time, the material tube 9 is slightly fed and the next pressure is applied. Extend and repeat.

In the above-mentioned drawing, first, the material tube 9 is drawn between the diameter-reducing portion 2 of the upper and lower roll dies 1 and the diameter-reducing portion 6 of the mandrel 5 to reduce the diameter and thickness. In the sizing portion 3 of the roll die 1, the outer diameter of the product pipe 11 is determined. Diameter reduction part 2 and sizing part 3 of roll die 1
The final size of the product tube 11 is determined by the final point 13 of the diameter reducing action portion of the mandrel 5 corresponding to the boundary point 12 of the mandrel 5, and the small diameter portion 7 on the rear end side from the final point 13 of the diameter reducing action portion does not contribute to the machining. It is a part.

Here, 8 is an area of the final stage of the diameter-reducing action portion, which is the thickness-reducing and expanding portion of the mandrel 5, and the width of the diameter-reduction action portion final-stage area 8 is larger than the diameter-reduction action portion final point 13. 1 on the radial side
It is the amount of elongation 14 corresponding to the total of the feed length and the elongation length in the draw. The thickness of the material tube 9 drawn in the final-stage region 8 of the mandrel 5 at the diameter-reducing portion is finally determined and the wall thickness is not further reduced, and only the outer diameter is sized for the roll die 1. The diameter is slightly reduced in part 3, and the outer diameter
The inner diameter is determined. Therefore, when a mold having a concave pattern is cut in the area of the final-stage area 8 of the diameter reducing action portion, this is transferred to the inner surface of the product pipe 11 to form a floating pattern. At this time, if the mandrel 5 and the material pipe 9 remain attached to each other, that is, if they are still in the mold matching state, the pattern that could be bent at the next material feeding will be scraped, but fortunately with cold pilger companding, As shown in FIG. 5 (b), when the roll die 1 is separated from many material tubes 9, the tube which is a little lazy at the time of drawing is inflated by spring back and separated from the mandrel 5 a little. Therefore, if the unevenness is within the springback amount, the pattern formed in the final stage area 8 of the diameter reducing action portion can be transferred. Therefore, when it is desired to form a deep recessed pattern in the final stage area 8 of the mandrel 5 for reducing the diameter, it is preferable to increase the taper of this portion.

As the shape of the pattern formed on the mandrel 5, it is preferable that the concave pattern is a smooth concave pattern such as a circular pattern or an oval pattern that is regularly or randomly arranged. Types of plastic granules,
An appropriate shape can be selected depending on the shape.

As a method of forming a concave pattern on the mandrel,
Mechanical cutting, grinding, drilling and the like are used for large patterns, and knurling and etching are also used for fine patterns. As described above, the place to attach is the final stage area 8 of the diameter reducing action part of the mandrel 5 which is determined by the relationship with the caliber shape of the roll die 1.
Part of. However, it is convenient to expand the patterning area a little to the small diameter side, because it is possible to deal with some dimensional deviation in actual operation.

[0014]

Example A metal pipe, which is a raw material pipe, was reduced in diameter and thinned by a cold pilger mill to manufacture a long thin pipe which was a product pipe. The metal mother tube used is made of SUS304 stainless steel, and its dimensions are an outer diameter of 45 mm, an inner diameter of 37 mm, and a wall thickness of 4 mm. This has an outer diameter of 25.4 mm, an inner diameter of 21.4 mm,
It was drawn to a wall thickness of 2 mm. The reduction ratio was 3.5. The feed was 6 mm. Therefore, the growth of the finished product is 6 mm x 3.5
= 21 mm, the length of progress of the product pipe in one cycle is 21 mm + 6
mm = 27 mm.

Embodiment of Mandrel Processing Section: FIG. 1 shows a cold pilger mandrel 5 according to an embodiment of the present invention. The dimensions of the cold pilger mandrel 5 in this example are as follows: the total length is 750 mm, and the diameter-reducing portion 6 is 445.
mm, the maximum diameter portion of the diameter reducing action portion 6 is 35 mm, the diameter of the small diameter portion of the diameter reducing action portion final stage region 8 of the diameter reducing action portion 6 is 21.4 mm,
The length is 21 mm. The length of the portion where the recessed pattern is formed is 21 mm which is the length of the final stage area 8 of the diameter reducing action portion, and the portion from the final point 13 of the diameter reducing action portion to 10 mm further rearward is added 31
mm.

FIG. 2 schematically shows the surface shape of the recessed pattern formed in the final stage area 8 of the mandrel 5 for reducing the diameter. In this embodiment, the depth 16 is 0.
3mm, as seen in (b), the width 17 has 3 oval recesses 15 on the circumference of the mandrel 5, ie, (c)
As can be seen in Fig. 4, four elliptical recesses 15 each having a major axis over 40 ° are arranged at 50 ° intervals, and as shown in (b), 15 mm apart at the center position. Similarly, four elliptical recesses 15 are provided on the circumference of the mandrel 5 by rotating 45 ° to form two elliptical recesses 1.
5 patterns are formed.

FIG. 3 shows a vertical cross section of the mandrel 5 of the recessed pattern forming portion. The size of the elliptical recess 15 is appropriately selected according to the properties of the transportation material transported by the air transportation tube and the number on the circumference. The formation of these elliptical recesses 15 was formed by cutting.

A metal mother tube which is the material tube 9 is cold-pilger-rolled using the mandrel 5 in which the pattern of the elliptical recess 15 is formed, and the inner diameter of the metal tube is reduced at the same time as thinning and thinning. The floating pattern 19 was processed to form a metal pipe, which is the product pipe 11 with the internal floating pattern 19 shown in FIG.

The cold pilger rolling conditions in this case were a feed amount of 6.0 mm and a rotation speed of 100 rpm. The obtained product tube 11 with a floating pattern has an outer diameter of 25.4 mm,
The thickness was 2.0 mm and the length was 15,000 mm. As shown in FIG. 5 (a), the material pipe 9 is slightly squashed by the pressing force 20 of the roll die 1 in the arrow direction at the time of drawing, but as shown in FIG. Then, it returns to a circular shape, and the product tube 11 separates from the mandrel 5.
Therefore, the formed floating pattern on the inner surface of the pipe is sent without being crushed.

FIG. 4 shows the shape of the inner surface of the inner surface floating pattern 19 of the metal tube with the inner surface floating pattern formed by using the mandrel shown in FIG.

In the present embodiment, since the floating pattern was formed extremely uniformly on the inner surface of the metal tube, the air transport tube using the metal tube with the inner surface floating pattern of the small diameter according to the present invention is used on the inner wall of the tube during air transportation. No plastic particles were attached by rubbing, so no strip-like delamination occurred and no blockage of the transport tube.

[0022]

INDUSTRIAL APPLICABILITY As described above, the metal tube with the inner surface floating pattern of the present invention is used for pellets transported by air transportation,
Plastic particles such as chips, granules, or flakes do not rub against the inner wall of the pipe during air delivery to grow as a thin film, and therefore strip-shaped delamination does not occur and There is no blockage and the inside of the pipe is easy to clean. When the mandrel of the present invention is used, in the production method of the present invention using a cold pilger mill, it is possible to easily produce a long and thin metal tube with an inner surface floating pattern, which has been difficult in the past. Therefore, since the metal tube with the inner surface floating pattern of the present invention has a wide variety of lengths and diameters, such as a long thin tube, it can be applied to a wide range of applications as an air transportation tube. Furthermore, since the method of the present invention forms a floating pattern on the inner surface of the metal pipe at the same time as the diameter reduction and thinning rolling of the metal pipe by the cold pilger mill, it does not require a dedicated device, It has an excellent effect that it can be easily carried out only by processing a part of the surface and that a metal tube with an inner surface floating pattern can be obtained at low cost.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a relationship between a roll die, a mandrel, and a metal tube during drawing.

FIG. 2 is a diagram schematically showing the surface shape of a cold pilger mandrel and the dimensions of an elliptical depression.

FIG. 3 is a diagram showing an enlarged cross-sectional view of an elliptical depression of a mandrel.

FIG. 4 is a view showing a metal tube having a floating pattern formed on the inner surface.

FIG. 5 is a diagram showing deformation and springback of a metal tube during drawing.

[Explanation of symbols]

 1 roll die 2 diameter reducing part 3 sizing part 4 roll die shaft 5 mandrel 6 diameter reducing action part 7 small diameter part 8 diameter reducing action part final stage area 9 material pipe 10 diameter reducing pipe part 11 product pipe 12 boundary point 13 diameter reducing Final point of action part 14 Elongation amount 15 Elliptical recess 16 Depth 17 Width 18 Center angle 19 Lifting pattern 20 Pressurizing force 21 Fixed rack gear 22 Pinion gear 23 Crankshaft connecting rod 24 Metal

Claims (3)

[Claims] 1. A metal tube with an inner surface floating pattern, which has a floating pattern formed on the entire inner surface of the metal tube by reducing the diameter and thinning it with a cold pilger mill. 2. A cold pilger mill for cold-rolling a seamless metal tube, wherein the metal tube is cold-rolled using a mandrel having a concave pattern all around the final stage region of the mandrel's diameter-reducing portion. The method for producing a metal tube with an inner surface floating pattern according to claim 1, characterized in that. 3. The mandrel for producing a metal pipe with an inner surface relief pattern according to claim 1, wherein the mandrel of the cold pilger mill is provided with a recessed pattern on the entire circumference of the final stage region of the diameter reducing portion.