JP2005034899A - Deep-drawing method and deep-drawing cylindrical vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deep-drawing vessel composed of a stainless steel having ≥3 drawing ratio, suitable for a body for stainless steel-made extinguisher without applying an intermediate annealing. <P>SOLUTION: When a cylindrical vessel composed of austenitic stainless steel is produced with a reverse redrawing, a first drawing is performed with a warm drawing and the reverse redrawing is performed with an opposed hydraulic drawing. The heating temperature in the warm drawing is made to be 80-130°C, and the hydraulic pressure in the opposed hydraulic drawing is made to be 10-20 MPa. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a deep drawing method used for manufacturing a cylindrical container made of stainless steel, particularly a deep drawing method suitable for manufacturing a stainless steel fire extinguisher body, and a deep drawn cylinder manufactured by the processing method. Concerning the container.

  Conventionally, a cylindrical metal container with closed ends is used for the body of a fire extinguisher. There are two types of metal containers, a three-piece structure and a two-piece structure. Recently, from the viewpoint of cost reduction, a shift from a three-piece structure to a two-piece structure has been attempted.

  In the three-piece structure, a fire extinguisher body is manufactured by winding a plate material to form a cylindrical body, and closing both end openings of the body with bowl-shaped end plates. On the other hand, in the two-piece structure, a cylindrical container with a bottom is manufactured by deep drawing, and an end portion on the opening side is closed with an end plate to manufacture a fire extinguisher body.

  Among the deep drawing processes, reverse redrawing process, which will be a problem later, is described in detail in Non-Patent Document 1.

Akira Hashimoto, “Press Drawing”, 14th edition, Nikkan Kogyo Shimbun, November 30, 1975, p. 89-96

  By the way, the material of the fire extinguisher body was formerly plain steel, but recently, higher strength stainless steel has been attracting attention.

  However, stainless steel is inferior in workability compared with ordinary steel. For this reason, the thing of a 2 piece structure cannot be manufactured, but there existed a problem limited to a 3 piece structure. This is because the deep drawing ratio of the bottomed cylindrical container used for the three-piece structure exceeds 3, and such high drawing deep drawing is difficult with stainless steel. For this reason, the stainless steel fire extinguisher body is limited to a three-piece structure, and there is a problem that the manufacturing cost increases.

  An object of the present invention is to provide a stainless steel deep drawing method capable of a processing ratio of 3 or more. Another object of the present invention is to provide a deep drawn cylindrical container having a drawing ratio of 3 or more while being made of stainless steel.

  In order to achieve the above object, the present inventor has focused on redrawing, particularly reverse redrawing. Reverse redrawing is a processing method in which redrawing following the first drawing is performed in a direction opposite to the direction of the first drawing. In this processing method, the material is turned over, and a relatively large drawing ratio can be secured. However, in the case of stainless steel, it is difficult to ensure a drawing ratio of 3 or more unless intermediate annealing is sandwiched between the first drawing and the reverse redrawing.

  That is, in the case of stainless steel, a drawing ratio of 3 or more can be achieved by reverse redrawing and using intermediate annealing. However, if intermediate annealing is adopted, annealing costs are required, and reverse redrawing subsequent to the first drawing cannot be performed continuously at the same position as the first drawing, resulting in increased costs due to increased man-hours. Is also a problem. For this reason, the reverse redrawing method which can be continuously implemented in a fixed position, without using intermediate annealing together is calculated | required.

  Therefore, the present inventor has studied various methods for increasing the drawing ratio in reverse redrawing without depending on intermediate annealing. As a result, it is possible to secure a drawing ratio of 3 or more without intermediate annealing by making the first drawing process warm and performing counter-hydraulic processing by reverse redrawing following the first drawing process. It has been found that a two-piece structure is also possible in a steel fire extinguisher.

  The deep drawing method of the present invention has been developed on the basis of such knowledge, and in producing a cylindrical container made of stainless steel by reverse redrawing, the first drawing is warm drawing and reverse redrawing. The drawing process is a counter hydraulic drawing process.

  Further, the deep drawn cylindrical container of the present invention is a drawn container having a drawing ratio of 3 or more made of stainless steel manufactured by the deep drawing method.

  Warm drawing is a processing method in which the punch is unheated (usually cooled), and the drawing is performed by heating the material (blank) between the die and the plate presser. Drawing is improved by applying a temperature gradient in which the flange portion is heated and the punch shoulder is cooled. Opposite hydraulic pressure drawing is a function in which the hydraulic pressure in the hydraulic dome replaces the female die, and the hydraulic pressure in the dome is drawn while pressing the material evenly into the male shape during molding. It is a method to do.

  Deep drawing with a drawing ratio of 3 or more is possible without intermediate annealing for stainless steel by using the first drawing as warm drawing and the subsequent reverse redrawing as counter hydraulic drawing. Become. By omitting the intermediate annealing, both processes are continuously performed at the same position, that is, in one machine, and high processing efficiency is ensured. The counter hydraulic drawing is significant in that it can be carried out at a fixed position following the warm drawing.

  The present invention is applicable to a deep-drawn container used for a stainless steel fire extinguisher body. Incidentally, the dimensions of the deep-drawn container are usually an inner diameter of 80 to 200 mm and a wall thickness of 1.0 to 2.0 mm. As the stainless steel, austenitic stainless steels such as SUS304 and SUS316L, in which warm forming is particularly effective, are preferable.

  The heating temperature in the warm drawing process is preferably 80 to 130 ° C. If this temperature is too low, work hardening occurs and tearing occurs in the second step. If it is too high, the material may be similarly broken. Further, the hydraulic pressure in the counter hydraulic drawing process is preferably 10 to 20 MPa. When this hydraulic pressure is too low, the slipping of the material becomes worse. If it is too high, the deformation of the sliding-in portion of the material will be severe and will be easily broken.

  In the deep drawing method of the present invention, when a cylindrical container made of stainless steel is manufactured by reverse redrawing, the first drawing is set as warm drawing and the reverse redrawing is set as counter hydraulic drawing. A drawing ratio of 3 or more can be secured without using intermediate annealing. Thereby, both processes can be efficiently performed at the same position.

  The deep-drawn cylindrical container of the present invention is a container having a drawing ratio of 3 or more produced by the above-described deep-drawing method, and is excellent in economic efficiency because it can be produced efficiently without using intermediate annealing. By using this for the body of a stainless steel fire extinguisher, a two-piece structure becomes possible, and a great effect is obtained in reducing the price of the stainless steel fire extinguisher.

  Embodiments of the present invention will be described below with reference to the drawings. 1A to 1C and FIGS. 2A to 2C are process diagrams of a deep drawing method showing an embodiment of the present invention.

  The deep drawing method of the present embodiment is used for manufacturing a stainless steel fire extinguisher body having a two-piece structure. More specifically, a deep drawing cylindrical container having a drawing ratio of 3 or more used for the body is subjected to intermediate annealing. It is an efficient manufacturing method at a fixed position by reverse redrawing without pinching.

  First, the processing apparatus will be described. The processing apparatus includes a cylindrical outer punch 2 installed on a base 1, an annular plate retainer 3 disposed outside the outer punch 2, and a liftable die 4 disposed opposite to the plate retainer 3. And an elevating inner punch 5 disposed on the outer punch 2 through the center of the die 4.

  The outer punch 2 is fixed on the base 1 and functions as a male mold for the die 4 in the first drawing process, and functions as a female mold for the inner punch 5 in the reverse redrawing process (opposite hydraulic drawing process).

  The annular plate retainer 3 is configured to be movable up and down along the outer surface of the outer punch 2. As the die 4 descends, the disc-shaped material 10 is sandwiched between the die 4 and the material 10 is sandwiched. In this state, it goes down with the die 4. The plate holder 3 and the die 4 incorporate heaters 7 and 8 in order to heat the flange portion of the sandwiched material 10.

  The die 4 performs a first drawing process on the material 10 in cooperation with the outer punch 2. That is, as the die 4 descends, the male outer punch 2 is inserted into the die 4, and the material 10 is pushed into the die 4.

  The inner punch 5 performs reverse redrawing (opposite hydraulic drawing) on the material after the first drawing in cooperation with the outer punch 2. That is, when the inner punch 5 is inserted into the outer punch 2, the first squeezed container 11 is pushed into the outer punch 2, and at the same time, the first squeezed container 11 is moved into the inner punch 5 by the hydraulic pressure in the outer punch 2. Pressed against the surface.

  Next, a deep drawing method using this processing apparatus will be described.

  When the material 10 is set, as shown in FIG. 1A, the die 4 and the inner punch 5 are raised to the initial position on the outer punch 2, and the plate retainer 3 has an upper surface that is the upper surface of the outer punch 2. Ascend to the initial position where it becomes the same level. In this state, an austenitic stainless steel disc is placed on the plate holder 3 as the material 10.

  When the setting of the material 10 is completed, the die 4 is first lowered to a position where the die 4 hits the material 10 as shown in FIG. As a result, the material 10 is sandwiched between the plate holder 3 and the die 4 with a predetermined pressure. Further, the material 10 is heated to a predetermined temperature by the heaters 7 and 8. The outer punch 2 is not heated.

  Then, as shown in FIG. 1C, the die 4 is further lowered while the material 10 is held between the plate presser 3 and the outer punch 2 is inserted into the die 4. As a result, while the flange portion of the material 10 is heated, the material 10 is drawn into the die 4 and formed in the cup-shaped first squeezed container 11. Thus, the first drawing process is performed warm.

  When the first drawing is finished, the inner punch 5 is lowered and inserted into the outer punch 2 through the die 4 as shown in FIGS. As a result, the cup-shaped first squeezed container 11 covering the outer punch 5 from above is pushed into the outer punch 5 while turning over to form the re-squeezed container 12 as the final product.

  When the first squeezed container 11 is pushed into the outer punch 2 by the inner punch 5, the inside of the outer punch 2 becomes a hydraulic dome and presses the material against the surface of the inner punch 5 by hydraulic pressure. As a result, the drawability is improved, and the redrawable container 12 made of stainless steel having a draw ratio of 3 or more is fixed in position without interposing the intermediate annealing, coupled with the improvement of drawability by performing the first drawing process in the warm. It is manufactured efficiently.

  By this deep drawing method, an attempt was made to produce a deep drawn cylindrical container having an inner diameter of 132.6 mm and a depth of 345 mm from a SUS304 blank (diameter 452 mm, plate thickness 1.2 mm) (drawing in the first drawing process). 2), drawing ratio in reverse redrawing process 1.68, total drawing ratio 3.35). This container assumes a two-piece stainless steel fire extinguisher body. The material heating temperature in the warm drawing process was 100 ° C., and the hydraulic pressure in the counter hydraulic drawing process was 15 MPa. Despite drawing stainless steel with poor workability at a high drawing ratio of 3 or more, it was possible to produce a sound deep-drawn container without tearing or wrinkling.

  The reverse redrawing used here is an effective processing method for securing a drawing ratio, and is considered an indispensable method for securing a drawing ratio of 3 or more with stainless steel. However, the reverse redrawing of stainless steel is a very difficult process with a large load on the material, and the significance of performing the first drawing process warmly and the reverse redrawing process as counter hydraulic processing is important. is there.

  By the way, in the drawing process from the above-mentioned blank, if the first drawing process is performed cold, the first process can perform the drawing process of about the same degree. Reverse redrawing of the process becomes impossible, and general redrawing must be employed. As a result, the aperture ratio in the second step is about 1.2, and the total aperture ratio is limited to about 2.4. Also, even if the first drawing is performed warmly, if counter hydraulic processing is not employed in the reverse redrawing in the second step, the resistance to material slipping is large and breakage occurs immediately. The ratio is limited to a general redrawing level, and the total drawing ratio is also limited to about 2.4. In other words, this degree of drawing ratio is the upper limit when intermediate annealing is not sandwiched by the conventional method.

  In the above-described embodiment, the reverse redrawing process is performed at room temperature. However, the warm drawing process may be performed similarly to the first drawing process.

(A)-(c) is process drawing of the deep drawing processing method which shows one Embodiment of this invention, and shows 1st drawing. (A)-(c) is process drawing of the same deep drawing processing method, and shows reverse redrawing processing.

Explanation of symbols

1 Base 2 Outer punch 3 Plate retainer 4 Dies 5 Inner punch 7, 8 Heater 10 Material (blank)
11 First drawn container 12 Deep drawn container (product)

Claims (4)

  A deep drawing method characterized in that when a cylindrical container made of stainless steel is manufactured by reverse redrawing, the first drawing is warm drawing and the reverse redrawing is counter hydraulic drawing.   The deep drawing method according to claim 1, wherein the intermediate drawing is not performed between the first drawing and the reverse redrawing, and both are continuously performed at the same position.   A deep drawn cylindrical container manufactured by the deep drawing method according to claim 1 or 2, wherein the drawing ratio is 3 or more.   The deep-drawn cylindrical container according to claim 3, which is used for a stainless steel fire extinguisher body.

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