JP3408121B2 - Mold for forming spiral strips on metal tubes - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process of plastically processing a metal strip unwound from a coil by applying it to a press machine using a progressive die. The present invention relates to a forming die for forming a spiral strip on a metal tube, in which beading can be performed on a tubular portion following a step of forming a tubular portion by drawing. 2. Description of the Related Art FIG. 13 shows an example of a conventional manufacturing process for a fuel filler fitting used for a fuel tank of an automobile or the like. FIG.
The fuel supply fitting 201 shown in FIG. 3 (f) is provided inside an upper part of an outer cylinder 203 having a mounting flange 202 at a lower end thereof.
The inner cylinder 204 is formed by folding processing,
4, a spiral strip a for screwing a cap (not shown)
Is formed using a roll threading machine. [0003] The outline of the forming process of the fuel filler fitting 201 will be described with reference to FIGS. 13 (a) to 13 (e). First, a disk-shaped material 200 made by stamping a metal plate is used. (A) is drawn as shown in (b) to form a cap-shaped outer cylinder 203. Next, about 2/3 of the upper part of the overall height of the outer cylinder 203 is turned inward as shown in (c) to form the inner cylinder 204, and the end face b at the tip is punched out (d) ). Thus, the inner cylinder 2
If the 04 is protruded below the outer cylinder 203, a state in which a roll threading machine can be applied to this protruding portion is provided. Therefore, a spiral strip a is formed on the protruding portion using a roll threading machine (not shown) as shown in FIG. Finally, using a specially made press mold,
As shown in (f), when the portion of the inner cylinder 204 where the spiral strip a is formed is pulled up, the fuel filler fitting 201 having a desired shape is completed. [0005] The above-mentioned conventional molding method has major drawbacks as listed below. (A) In order to allow the inner cylinder 204 to be hung on a roll threading machine, a complicated and wasteful process of once lowering the inner cylinder 204 more than necessary and then pulling back the excessively lowered portion is required. (B) Since a roll threading machine is used to form the spiral strip a, a progressive-feed die which can continuously form a product of a desired shape from a coil-wound metal strip and has extremely high productivity was used. Press molding cannot be used. (C) Therefore, it is necessary to rely on extremely inefficient transfer molding in which individual works are processed stepwise while being conveyed to the next stage. (D) Therefore, more workers and considerably more work space are required. [0006] Therefore, an object of the present invention is to provide a helical strip for a metal pipe which uses a progressive die having extremely high productivity, enables continuous processing, and can sufficiently improve the dimensional accuracy of the helical strip to be formed. An object of the present invention is to provide a forming die. [0007] In order to achieve the above object, a forming die for forming a spiral strip on a metal tube according to the present invention is provided.
A metal tube is formed in a cylindrical shape, with spiral projections (grooves) provided on an outer peripheral surface thereof, and divided into a plurality of split molds along a radial split surface extending from the axis to change the outer diameter. And a diameter reducing biasing means of the core type, and a spiral groove (projection) is formed on the inner peripheral surface of the core type, and along a radial division surface extending from the axis. A plurality of split molds, the inner diameter of which is variable, the surrounding mold disposed around the outer periphery of the core mold, and the enlarging biasing means of the surrounding mold, and the core mold and the surrounding mold. A mold clamping means for expanding and reducing the diameter against the urging force of each of the urging means,
In order to improve the shape accuracy of the spiral strip to be formed, the projecting shapes of the spiral projections provided on the surrounding mold are made to differ in a stepwise manner, and the radial directions of the respective radial division surfaces are shifted by a predetermined angle. It is characterized by comprising a combination of a plurality of molding dies arranged in a line in a progressive die. FIG. 1 is a perspective view showing an embodiment in which the present invention is applied to the manufacture of a fuel filler fitting to be mounted on a gasoline tank or the like of an automobile. This will be described with reference to FIG. 1 and 2 show a vertical cross section and a planar shape of the fuel filler fitting 100. FIG. This refueling metal fitting 1 is made by feeding a long metal plate into a progressive die and continuously pressing it.
00 is formed in a short cylindrical shape having a double wall structure,
The inner cylinder 101 is provided with a spiral strip a for screwing a cap (not shown). At the lower end of the outer cylinder 102,
A bracket 103 for attachment to the tank is provided. 10
4 is a ventilation hole. FIGS. 3 to 5 show a schematic configuration of a molding die according to the present invention for forming a spiral strip a in the fuel filler metal fitting 100 at an intermediate stage of the press molding process. FIG.
Shows a longitudinal section of a forming die in a state where an oil supply fitting (work W), which has been processed from a metal plate to a stage prior to the step of forming the spiral strip a, is set. FIG. 4 shows a vertical cross section of a molding die in a state where the spiral strip a has been formed on the work. First, the schematic configuration of the molding die will be conceptually described. The molding die is composed of a combination of a lower die and an upper die, and the inner surface of the spiral strip a is formed on the upper surface of the lower die. A column-shaped core mold provided with a spiral groove for forming a spiral groove, and a cylindrical surrounding mold provided with a spiral projection for forming the outer surface of the spiral strip a on the lower surface of the upper mold is formed by a core. It is suspended coaxially with the mold. In order to make the outer diameter variable, the core mold is divided into a plurality of molds along a radial dividing surface extending from the axis thereof, and the core mold is provided with a diameter reducing urging means. On the other hand, the surrounding type is also divided into a plurality of split dies along a radial split surface extending from the axis in order to make the inner diameter variable, and a diameter expanding urging means is provided. Further, when the upper mold is pressed against the lower mold, the core mold and the surrounding mold are expanded and contracted in diameter against the respective urging means, and mold clamping means for press-forming the spiral strip a is provided. are doing. Next, a specific example of the detailed configuration of the molding die will be described. As shown in FIG. 3, the lower die 51 of the molding die 50 has an inner cam punch 1 (lower inclined cam: die clamping means) having a convex conical cam surface 1A, which is erected at the center of the upper surface. A holder 2 is provided. On its upper surface, a thick plate-shaped pad 3 provided with an insertion hole 3a for the inner cam punch 1 is supported by four lower springs 4 having relatively low spring force. The inner collet 6 (core type) having a concave conical cam surface 5 facing down on the shaft center portion is fitted on the convex conical cam surface 1A of the inner cam punch 1. ing. The outer shape of the lining collet 6 is formed in a cylindrical shape having a flange 6b provided on the outer peripheral surface at the lower end thereof, and a helical groove 6a for forming a helical strip a is formed on the outer peripheral surface.
Is provided. Further, in order to make the outer diameter of the inner collet 6 variable, a total of eight radial dividing surfaces c extending from the axis are provided.
It is divided into eight split dies 6A along (see FIG. 5), and each split die 6A is disposed on the pad 3 so as to be able to move back and forth in the radial direction of the lining collet 6. Then, the guide ring 7 also serving as a positioning and moving guide for each split mold 6A is fixed on the pad 3 while covering the flange 6b of the lining collet 6. A lining collet 6 is mounted on the guide ring 7.
The compression springs 8 serving as the diameter reducing urging means for always keeping the diameter reduced are assembled at a total of eight locations facing the outer peripheral surface of each split mold 6A. Next, the upper die 52 of the molding die 50 is provided on a lower surface of an upper die holder 12 connected to a ram of a press machine (not shown). ) Is suspended so as to surround the inner lining collet 6. Further, a guide ring 13 slidably fitted on the upper cam punch 11 is suspended from the upper holder 12 via four upper springs 14 having relatively strong spring force. On the inner peripheral surface of the upper cam punch 11, a conical cam surface 15 which is expanded downward is formed. Inside the upper cam punch 11, a beading collet (surrounding type) 17 having a conical cam surface 16 slidably in contact with the conical cam surface 15 formed on its outer peripheral surface is fitted. A spiral projection 17a for forming a spiral strip a is provided on the inner peripheral surface of the beading collet 17 having a cylindrical shape as a whole. Further, the beading collet 17 is divided into eight split dies 17A along a total of eight radial split surfaces d (see FIG. 5) extending from the axis in order to make the inner diameter variable. Each split mold 17A is mounted on the guide ring 13 so as to be able to move back and forth in the radial direction of the beading collet 17. The guide ring 13 is provided with expansion springs 18 serving as biasing means for keeping the beading collet 17 in an enlarged state at all times, in a total of eight places facing the outer peripheral surface of each split mold 17A. Assembled. Fig. 7 shows one split mold 17A
Was shown as a perspective view. As shown in FIG. 5 as a plan view of the lower die 51, guide posts 21 are provided upright on both side ends of the upper surface of the lower die holder 2. These two guide posts 21 and 21
Of the upper and lower dies 51 by loosely fitting them into guide tubes (not shown) which are vertically provided on both side ends of the lower surface of the upper die holder 12.
-52 are positioned relative to each other. FIG. 6 shows a spiral projection 17 provided on a beading collet 17 in order to improve the shape accuracy of the spiral strip a.
As shown in FIGS. 6 (a) and 6 (b),
A plurality of molds, which are different in a stepwise manner, in this case, two molds, each having a predetermined angle relative to the direction of each radial division surface d,
In this case, a state in which they are arranged side by side with a shift of 22.5 degrees is shown as a plan view of the main part. The arrows in the figure indicate the direction in which the workpiece is fed. Next, the fuel filler fitting 100 shown in FIGS.
The process of continuously press-forming a long metal plate using a progressive die into which the molding die of the present invention is incorporated will be described mainly with reference to FIGS. 9 to 12. First, on a metal strip fed from a roll,
Pilot piercing and hour piercing (A) are performed (Fig. 1
0). Next, first to fourth draw processing (B)
(E) and a restriking process (F) are sequentially performed to form the cap-shaped inner cylinder 101 in a stepwise manner. Subsequently, after piercing (G) for punching the top surface of the cap shape, burring (H) is applied to the edge of the punched hole. Portions that have completed each processing stage will be referred to as “work W”. FIG. 9 shows a vertical cross-sectional shape of the work W corresponding to the processing stages (B) to (H) described above. Next, using the above mold, the inner cylinder 101
Beading step (I) for forming a spiral strip a in
The process proceeds to (J) (see FIGS. 9 and 12). To do that, the upper die 5
2 is pulled up, and the inner collet 6 in the reduced diameter state of the lower mold 51 is pulled out.
Then, as shown in FIG. 3, the workpiece W after the processing step (H) is fitted to the outside. When the downward movement of the press (not shown) is started from this state, after the upper die 52 comes into contact with the lower die 51,
The lower spring 4 with a weak spring force is compressed first,
The concave conical cam surface 5 provided on the inner lining collet 6 is the convex conical cam surface 1 of the inner cam punch 1 erected on the lower die holder 2.
A is pushed. Accordingly, each of the split dies 6A constituting the inner lining collet 6 is pushed in the outer peripheral direction against the urging force of the compression spring 8. Therefore, the expanded lining collet 6 is in a state where the workpiece W is firmly gripped from the inner surface thereof. When the press machine continues to apply a pressing force to the upper mold 52, the upper spring 14 having a strong spring force starts to be compressed. Accordingly, the upper cam punch 11 descends along with the upper holder 12, and the conical cam surface 15
Is pressed against the conical cam surface 16 provided on the outer peripheral surface of the beading collet 17. At this time, since the beading collet 17 is already in contact with the lower mold 51, the horizontal component of the pressing force causes each split mold 17A to resist the expanding biasing force of the extension spring 18. And push it towards the center of the mold. Accordingly, the diameter of the beading collet 17 is reduced by itself. Since the diameter reducing force is enhanced by the wedge action of the conical cam surfaces 15 and 16, the helical projection 17a provided on the inner peripheral surface of the beading collet 17 forms It presses against the spiral groove 6a provided on the outer peripheral surface of the lining collet 6 with a strong force. Thus, the formation of the spiral strip a on the cylindrical portion of the workpiece W is completed almost instantaneously at a speed corresponding to the vertical movement cycle of the press machine (see FIG. 4). Thereafter, as shown in FIGS. 11 and 12, a primary draw process (K), a trim notch process (L), and a secondary to quaternary process for integrally forming the outer cylinder 102 around the outer circumference of the inner cylinder 101. The desired refueling fitting 100 is completed by passing through each of the press steps of the draw steps (M) to (O), the wrist step (P), and the trimming step (Q). Then, when the upper die 52 is raised, the inner lining collet 6 and the beading collet 17 are reduced in diameter and expanded in diameter, respectively, so that the fuel filler fitting 100 can be taken out. Incidentally, in the beading steps (I) and (J), in order to improve the shape accuracy of the spiral strip a,
As shown in FIG. 6, it is preferable to perform a pressing process in two stages using two molds. That is, as shown in FIG. 6A, the molding die in the previous stage shown on the left side of FIG. 6 changes the shape of the spiral projection 17a provided on each split mold 17A of the beading collet 17 into a desired shape. By making the shape round and slightly crushed, care is taken to avoid suddenly forming the workpiece W at an acute angle. Then, the molding die at the later stage on the right side of FIG.
As shown in FIG. 2B, the shape of the spiral projection 17a provided on each split mold 17A is made to match the desired shape. Further, in the latter stage, the direction of the radial division surface d of the beading collet 17 is set at an angle of 1/16 of 360 degrees, that is, 22.5 degrees, as compared with that of the former stage. It is installed in a state where it is rotated around the central axis. As a result, a strong forming pressure can be applied to the portion where the spiral strip a of the work W is formed in a stepwise and dispersed manner without difficulty, and higher forming accuracy can be obtained. In addition, the occurrence of defective molded products due to stress distortion can be almost completely eliminated. Alternatively, if the spiral strip a does not require a high degree of molding precision, such as a filler metal fitting, the molding die on the right side of FIG. 6 is omitted, and only the molding die on the left side is used. As shown in (1), a discontinuous spiral strip a may be intentionally formed. Even such a spiral strip a sufficiently fulfills the function of screwing the cap. In the above-described embodiment, the number of spiral strips a can be appropriately increased as needed.
Further, according to the method for forming a spiral strip according to the present invention, the invention is not limited to the production of a fuel filler metal fitting, but includes a cylindrical portion provided with a spiral strip.
Various other molded products can be mass-produced very efficiently. As is apparent from the above description, the use of the mold for forming a spiral strip on a metal tube according to the present invention provides the following practically superior effects. (A) A spiral strip can be formed much more efficiently than a conventional method using a roll threading machine. (B) For example, when a metal plate is press-formed to form a fuel filler, as long as a spiral strip is formed by a conventional roll threading machine, a progressive type with extremely high productivity cannot be used.
According to the mold of the present invention, it is possible to use a progressive die. (C) By arranging a plurality of molds in which the projecting shapes of the spiral projections provided on the surrounding mold are changed stepwise and the radial directions of the radial division surfaces are shifted by a predetermined angle,
A spiral strip with higher forming accuracy can be formed more easily.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of an embodiment in which the present invention is applied to the production of a fuel filler such as a gas tank, and the like. FIG. 2 is a plan view of the fuel filler fitting. FIG. 3 is a longitudinal sectional view showing a state in which a work is set on a lower mold of a molding die in a spiral strip forming step. FIG. 4 is a vertical cross-sectional view of the molding die at the stage when the spiral strip has been formed. FIG. 5 is a plan view showing a planar shape of the lower die, including a shape of a main part of the upper die. FIG. 6 is a plan view of a main part showing an embodiment in which two molding dies are arranged in a row, in which the shapes of spiral projections provided on a beading collet are different in a stepwise manner; It is the figure which showed the difference. FIG. 7 is a perspective view of a split mold included in the beading collet. FIG. 8 is a longitudinal sectional view of a work having a spiral strip formed by using a beading collet provided with a spiral projection having the shape of FIG. FIG. 9 Same as above. In the first half of each forming step, the work is sequentially changed in shape in the first half of the step of press-forming an oil filler from a metal plate using a progressive die in which the forming die of the present invention is assembled. FIG. FIG. 10 is a plan view showing a state in which a metal plate is sequentially processed in each forming step in the first half stage. FIG. 11 is a longitudinal sectional view showing a state where the work sequentially changes its shape in each forming step in the latter half of the above. FIG. 12 is a plan view showing a state in which a metal plate is sequentially processed in each forming step in the latter half of the above. FIG. 13 is a view showing an example of a conventional molding process of a fuel filler fitting. [Description of Signs] 50 Molding die 51 Lower die 52 Upper die W Work a Spiral strip c, d Radial split surface 1 Inner cam punch (lower inclined cam: mold clamping means) 1A Convex conical cam surface 2 Lower die holder 3 Pat Reference Signs List 4 lower die spring 5 concave conical cam surface 6 lining collet (core type) 6A split die 6a spiral groove 6b flange 7 guide ring 8 compression spring 11 upper die cam punch (upper slope cam: die clamping means) 12 upper die holder 13 Guide ring 14 Upper springs 15, 16 Conical cam surface 17 Beading collet (surrounding type) 17a Spiral projection 18 Extension spring 21 Guide post 100 Refueling fitting 101 Inner cylinder 102 Outer cylinder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B21D 51/38 B21D 17/02 B21D 22/02 B21K 1/56

Claims (1)

(57) [Claims 1] A cylindrical shape, spiral projections (grooves) are provided on the outer peripheral surface thereof, and a plurality of split dies are formed along a radial division surface extending from the axis. And a core type for externally fitting a metal tube, and a diameter reducing urging means of the core type, and a spiral groove (projection) on the inner peripheral surface of the cylindrical shape. Along with the radial division surface extending from the axis of the core, it is divided into a plurality of split molds, the inner diameter is configured to be variable, and the surrounding mold disposed around the outer periphery of the core mold, and the surrounding mold. A diameter enlarging means, and a mold clamping means for enlarging and reducing the diameter of the core mold and the surrounding mold against the urging force of each of the urging means. In order to increase the shape of the helical projection provided on the surrounding mold, the shape of the helical projection is changed step by step. Are arrayed a morphism direction progressive die in a state of shifting a predetermined angle at a time, helical Article mold for forming the metal tube, characterized in that it consists of a combination of a plurality of sets of molds.