JPH0115329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for forming circular tubes, and in particular to a method for forming circular tubes from a strip using a rotary swaging machine.

(Prior art and its problems) Roll forming and press bending are known as methods for forming circular tubes from flat plates. However, although the former has a fast forming speed, it requires large and expensive equipment because many rolls are arranged in a line, and it is difficult to deal with changes in pipe diameter or plate thickness, etc. The material is difficult to apply to tubing. Therefore, there was a problem in that it was not suitable for the recent trend of high-mix, low-volume production.

Examples of the latter method include the U-O molding method and the gradual molding method proposed by the present inventors. but,
In any case, forming is an intermittent process that synchronizes with the vertical movement of the press machine, which has the fatal disadvantage of slow processing speed and low productivity. The drawback was that secondary processing could not be made continuous or efficient. Furthermore, since the number of processing times per unit time is small, the unit processing power is large, and expensive equipment with a large capacity is required.

(Means for solving the problems) The present invention solves the conventional problems as described above,
A flat plate can be continuously formed into a circular tube with high productivity using small equipment with low processing power per unit, and forming processes such as welding processes, taper processing, and pre-fitting processes can be performed consistently and continuously. The aim is to provide a new method for forming circular tubes.

To achieve this objective, the present invention uses a rotary swaging machine and a special bending die to progressively form a flat plate into a circular tube.
In the past, it was generally only used for secondary processing (forging) such as taper processing, tip processing, and stepped processing of circular pipes. However, this rotary swaging requires a very large number of processing times per unit time.

Focusing on this feature, the present invention disposes a special non-rotating bending die consisting of a die and a punch in a rotary saging machine, and utilizes the rotary saging machine as a pressurizing means for the bending die. The plate is formed into a circular tube by gradually bending the plate from the edge to the same radius as the tube.

That is, the basic feature of the present invention is that the inlet groove is composed of side curved surfaces for edge bending on both sides and a straight or curved bottom surface connecting these side curved surfaces, and this inlet groove has a semicircular groove on the outlet side. A bending die consisting of a grooved die that tapers continuously so that the grooved die and a punch having a shape similar to the grooved die is inserted into a rotary saging machine so as not to rotate at all times, and the band is inserted into the bending die. The purpose is to apply pressure to the bending die by rotating a buckler around the outer periphery of the bending die while sequentially feeding the strip a predetermined length, thereby gradually bending the strip from both edges at the same radius as the tube.

In addition to the above-mentioned basic features, another feature of the present invention is that by rotating a rotary bending die having a groove shape that equally divides the circumference together with a bumper on the outer periphery, the bending die is used to finish form the entire circumference into a circular shape. It consists in using processes together.

This method is effective in improving cross-sectional accuracy;
Specifically, either a method in which the non-rotating bending die and a rotary bending die are placed in the same rotary saging machine, or a method in which they are placed in separate rotary swaging machines and carried out in tandem may be adopted. Can be done.

Although the present invention basically involves forming a tube with a circumference of a circle from a strip, it is also possible to form a semicircle, and unless otherwise specified, a semicircle is also considered a "circular tube."
shall be included in the

(Example) Examples of the present invention will be described below with reference to the accompanying drawings.

1 to 3 illustrate the method of forming a circular tube according to the present invention, in which numeral 1 denotes a bending die, which consists of a grooved die 2 and a punch 3. 4 is a rotary swaging machine, and 5 is a strip plate.

The bending die 1 basically has a structure as shown in FIG. That is, first, the grooved die 2 is provided with an inlet groove 20 on the inlet side, which is made up of side curved surfaces 21, 21 for edge bending and a flat bottom surface 22 that connects the side curved surfaces, and on the outlet side, the side curved surface 20 is formed. 21,
A semicircular groove 23 having the same radius as 21 is formed, and between the entrance groove and the semicircular groove, the bottom surface 22
and a bending line 24 that forms a boundary between the side curved surfaces 21, 21,
The groove width is gradually narrowed so that the grooves 24 are continuously adjacent to each other.

Next, the punch 3 has a shape similar to the grooved die 2, that is, a flat top surface 32 corresponding to the inlet groove 20 and side curved surfaces (punch shoulders) 31, 31 corresponding to the side curved surfaces 21, 21. It has a starting end 30 on the inlet side, and a semicircular groove 2 on the outlet side.
3, and the width between the starting end 30 and the semicircular part 33 is continuously narrowed. It is desirable that the semicircular groove 23 and the semicircular portion 33 have a predetermined length in order to apply compressive force to the tube in the final stage and improve the roundness.

FIGS. 5 and 6 show another bending die used in the present invention, which is effective in preventing the occurrence of waves and warpage at the edge of the plate. Specifically, the side curved surfaces 21, 21, the bottom surface 22, and the bending line 24 of the groove die in FIG.
24 is a continuous curve so as to form a convex shape toward the inner side of the groove from the inlet groove 20 to the outlet groove (semicircular groove) 23, and the groove depth of the inlet groove 20 and the outlet groove 23 remains the same. , the die upper surface 2 is concave with respect to the punch 3, and the outlet side is low and the inlet side is high.
The entire structure including parts 7 and 27 is formed into a curved line. The punch 3 is also configured to have a curved shape so as to correspond to the shape of the grooved die 2.

The grooved die 2 and the punch 3 have curved surfaces 28,
38, from the die top surfaces 27, 27 to the curved surface 2
Holes 29, 29 are drilled across the curved surface 38, and holes 39, 39 are concentric with the holes 29, 29 formed on the lower surface 37, 37 of the punch facing the upper surface of the die.
are drilled, and a positioning pin 40 is inserted into each.

The structure of the rotary swaging machine 4 is arbitrary, and in the illustrated one, the back curved surface 2 of the bending mold 1 is
A plurality of (four in the drawings) inner butts 41 having divided circumferential inner surfaces corresponding to numbers 8 and 38, an outer buckler 42 with a wedge 43 driven between them, and adjacent butts in the circumferential direction. It is equipped with a spindle 44 that connects through a side liner, and outer peripheral rollers 46 arranged at equal intervals that come into contact with and separate from the roller or arc surface 45 of the outer backer 42, and when the spindle 44 rotates or the spindle 44 rotates. The outer peripheral roller 46 is adapted to rotate in the opposite direction.

The bending die 1 is bent by a spindle 44,
42 is configured to be held in a non-rotating state even when it rotates. Although the means for this purpose is arbitrary, in the one shown, the bending die itself is equipped with a rotation stopper jig 6. 7 and 8 show this rotation stopper jig 6, which consists of a block 6b having a guide groove 61 corresponding to the width of the strip plate 5 and a block 6a in contact with the block 6b. In the case shown, it is provided on the block 6b on the punch side, and the groove bottom is aligned with the punch top surface 32. These blocks 6a and 6b are integrally connected to the entrance sides of the grooved die 2 and punch 3, respectively, and at least the entrance side portion has parallel surfaces 6 on the left and right.
It has a cross-sectional shape of 3,63.

On the other hand, the lid 7, which is attached to the inlet side of the rotary swaging machine 4 so as to be openable and closable, is formed with a hole 70 having a height that allows vertical movement of the blocks 6a and 6b, as shown in FIG. This hole 70 has parallel guide surfaces 71, 71 in contact with the parallel surfaces 63, 63.

When the rotation stop jig 6 is used, the bending die 1 is not rotated even by the rotation of the backers 41 and 42, and the grooved die 2 and punch 3 only move up and down. Furthermore, since the jig also serves as a material feed guide, feeding is performed with the center line of the bending die processing part and the center line of the strip accurately matching, thereby preventing twisting during forming.

For forming, bucklers 41 and 42 are installed between the outer circumferential rollers 46 as shown in FIG.
Insert the grooved die 2 and punch 3 into the grooved die 2 and the punch 3, and attach the blocks 6a and 6b of the rotation stopper 6 to the inlet sides of the grooved die 2 and punch 3 as shown in Fig. Insert the hole 70 of the lid 7 into the hole 70 and fix the lid to the machine.

In this state, the spindle 44 is rotated by the motor 47 and the flywheel 48, and the strip 5 is inserted between the blocks 6a and 6b by a predetermined length by an appropriate feeding means 50 such as a roll.

By doing this, the outer periphery of the bending die 1 can be bent 41, 4.
2 collides with the outer circumferential roller 46 while rotating, and a blow is applied to the bending mold 1 through the inner backer 41, and this force causes the bending mold 1 to
A vertical pressing force is generated on the grooved die 2 and the punch 3 that make up the strip plate 5, and the edge bending is performed on the strip plate 5 (Fig. 1a).
When it comes off from the outer peripheral roller 46, the backs 41, 4
2 moves in the radial direction due to centrifugal force, the grooved die 2 and the punch 3 are in a non-pressurized state, and the strip 5 can be fed (FIG. 1b).

Then, the groove die 2 and the punch 3 are opened vertically by feeding the strip plate 5, but at the next moment, the bucklers 41, 42 and the outer peripheral roller 46 collide again, and the pressure is applied again, and the edge bending is performed. (Fig. 1c). At the next moment, the pressure is not applied again, and the strip is fed (FIG. 1d).

Although the direction of impact applied to the bending die 1 from the inner bumper 41 is different between states c and a in FIG. Furthermore, the rotation stop jig 6 prevents the groove die 2 and punch 3 from rotating both when pressurized and when not pressurized.

Since the pressurization and depressurization of the bending die by the bucklers 41 and 42 are repeated at a very high frequency, the strip plate 5 is rapidly progressively formed into the desired tube shape and sent out from the outlet of the rotary swaging machine. .

To explain the forming state in detail, when one end of the strip plate 5 advances from the guide grooves of the blocks 6a and 6b to the entrance groove of the bending die 1 and becomes the pressurized state as shown in FIG. 1a or c,
The side curved surfaces 21, 21 of the grooved die 2 and the side curved surfaces 31, 31 of the punch 3 bend the edge portion of the plate beyond the bending lines 24, 24 to the same radius as the tube to be manufactured, and then, as shown in FIG. Or, at the stage where the strip plate advances to the next feed length in the non-pressurized state of d, the part closer to the center of the plate width than the bending line is bent to the same radius as the tube to be manufactured, and furthermore, such an edge The bending process moves toward the center of the sheet width for each feed length, and finally it is compressed from the radial direction by the semicircular groove 23 and the semicircular portion 33, and is sent out from the bending die 1 for each feed length.

The side curved surfaces 21, 21 of the groove-shaped die 2 are continuously close to each other in the longitudinal direction of the die, and the side curved surfaces 31, 31 of the punch 3 are similarly spaced continuously close to each other in the longitudinal direction. From this, the position of the bending line for edge bending the strip plate 5 gradually shifts toward the center of the plate width in the longitudinal direction, and the degree of forming continuously increases. Therefore, it becomes a circular tube through a smooth deformation process.

Methods for forming circular tubes from strip plates include circular bending, in which the entire plate is bent at the same radius and the radius is gradually made smaller, and center bending, in which the plate is bent from the center to the same radius as the tube. There is a method. U-O forming belongs to the latter category, and the path length of the plate edge is very large, about 4.9 times the radius, and it is also quite difficult to suppress edge waves and improve roundness during U-bending, which is preforming. The trajectory length of the former is approximately 4.4 times the radius.

On the other hand, in the method using the bending die of the present invention, the trajectory length of the plate edge is the shortest, approximately four times the radius, and the bending edges 24, 24 continuously change from the inlet to the outlet. The tube is bent repeatedly to the same radius as the tube. Therefore, there is no need for U-forming, which has a negative effect on the product, and shape defects are less likely to occur.

In the case of U-O forming, performing progressive bending requires a large overall mold length for the U-forming part and the O-forming part, but in the case of the present invention, the mold length is significantly reduced. be able to.

The above is the basic method of the present invention, and in the one shown, the semicircular part 33 is supported by the fins 330 at the exit of the punch 3, so the flange end that has been formed comes into contact with the fins 330 and remains as it is. With this method, it is not possible to form a full circumference circular tube. However, with this mold structure alone, it is possible to form semicircular tubes and 5/6 circumferential tubes.

Next, the case of forming a circumferential circular tube will be explained. In order to mold the bending die 1 as described above while holding it non-rotating in the rotary swaging machine 4, as shown in FIG. A pair of finishing bending dies 2', 3' having corresponding semicircular grooves 23' are inserted into the groove die 2.
and the punch 3, which are integrated or separated in series, are arranged in the inner peripheral space of the inner backer 41 of the rotary swaging machine 4, and the spindle is rotated as described above. Figure 1a
It is sufficient to repeat the operations of steps .about.d, and thereby a tube with a closed cross section can be continuously formed from the strip plate with high precision.

In addition, as another method for forming a circumferential circular tube,
A rotary bending mold 9 consisting of a set of dies 9a and 9b each having groove-shaped surfaces 23 and 23 that equally divide the circumference.
There is a method of using the above-mentioned non-rotating bending mold 1 together. Specifically, the two types of bending molds 1 and 9 are installed in separate rotary swaging machines 4 and 4, and primary and secondary forming is performed in tandem to form the strip plate into the target circular tube. One of them is the method.

Another method is to arrange the non-rotating bending die 1 and the rotary bending die 9 in the same rotary swaging machine 4 for molding.

This method will be explained in detail in Figures 12 to 13.
The figure shows this forming method, in which a bending die 1 as illustrated in FIGS. Rotation is stopped using a stop jig 6 or the like, and the rotary bending die 9 is placed in a region on the exit side of the bending die 1. This rotary bending die 9 may have a guide portion formed at its entrance, and its back portion has an angle 92 through which the rotation of the spindle is transmitted.

If the spindle 44 is rotated and the strip plate 5 is fed in a predetermined length at a time, the first
As shown in Figures a to 1d, the grooved die 2 and punch 3 are pressurized by fast rotating bucklers 41 and 42 and move up and down at a high frequency, so that the strip plate 5 is moved from the edge of the plate to the same radius as the tube. 13a, i.e. at the entrance of the bending die 1 the strip 5 is almost flat, but as it enters the bending die 1,
At the exit part, the flange end is molded to a slightly open state as shown in Figure 13b,
In this state, it advances to the guide portion of the rotary bending die 9.

Due to the rotation of the spindle, this rotary bending die 9 rotates along with the bucker 41 around the outer periphery of the tube 5' which is in the process of being formed, and the bucker 42 collides with the outer peripheral roller 46.
Press a and 9b to impact the tube 5'. 13th
Figure c shows this state. At the next moment, the bucker 42 and dies 9a, 9b released from the outer peripheral roller 46 are opened by centrifugal force and become in a non-pressurized state.
By repeating this motion, a cylinder with a high precision all around the circumference with joined ends is formed and is sequentially sent out from the rotary swaging machine 4. FIG. 14 shows the state of the molded product produced by this method.

In addition, if you want to perform processes such as tapering, tipping, stepping, or shaping the formed pipe without welding, install the necessary dies on the same rotary swaging machine or another rotary swaging machine. Conventional swaging may be performed. When welding, it is sufficient to place a welding machine on the exit side of the rotary swaging machine, and in the case of the present invention, this welding process is faster and more continuous than the press forming method. , good followability can be obtained, and automation can be easily achieved.

In addition, in the present invention, a strip plate with holes may be used, and a tube with holes can be easily formed.

Next, a specific example of forming a tube according to the present invention will be described.

(1) The rotary swaging machine used in the experiment is a spindle-driven type (spindle rotation speed
245r.pm), the outer bender (head is a 20φ roller) in 4 directions (90 degree intervals) contacts the outer peripheral rollers (48φ, 12 rollers) to apply pressure (2) The bending type is Those shown in Figs. 5 and 6 were used. The total length was 90 mm, the outer diameter was 50 mm, the bend line interval of the inlet groove was 19.36 mm, and the outlet groove radius was 8 mmφ, which was the same as the radius of the tube to be formed. The length of the molded part is approximately 9.4 times the pipe diameter (75 mm).

The rotation stopper jig has a total length of 150 mm and a width of 30 mm, and a guide groove with a width corresponding to the strip plate was formed on the block on the punch side.

(3) The material of the strip is SPC, the thickness is 0.59mm, the width is 11.6mm(a),
There were three types: 17.0mm (b) and 21.2mm (c). The strip feeding speed was 1.3 m/min, and the reciprocating motion cycle of the bending die was 49 (cps).

(4) When circular tubes were formed from the strip under the above conditions, the strip in (a) was a semicircular tube, the strip in (b) was a 3/5 circumferential tube, and the strip in (c) was a 5/5 circumferential tube. Six circumferential tubes were individually molded, each with a good cross-sectional shape and little warpage in the longitudinal direction.

(5) Next, a full circumference circular tube was formed using a combination of the above bending die and a rotary bending die. The rotary bending mold is
It was a two-part mold with a semicircular cross section (6.4 mm in major axis, 5.4 mm in short axis, and a slope of 3.3 degrees at the taper part), and was arranged in series on the exit side of the bending mold. The strip is the same as (b) above.
(c) was used.

At the same time, a rotary bending die was placed in a rotary swaging machine for the bending die and another rotary swaging machine, and secondary molding was performed on the semi-formed product sent out from the bending die.

(6) As a result of the above, a full-circumference tube with the tube joints completely adhered was formed. The results of measuring the diameter and wall thickness distribution of the obtained tubes are shown in Figure 15, and the difference between the maximum and minimum diameters for each tube is 0.04 mm.
It can be seen that the increase in plate thickness is very slight and uniform over the entire circumference of the tube, and that a highly accurate all-circumference tube can be formed.

(Effects of the Invention) According to the present invention as described above, there is an inlet groove on both sides that is composed of side curved surfaces for edge bending and a linear or curved bottom surface connecting these side curved surfaces, and this inlet groove is on the outlet side. A rotary swaging machine is equipped with a bending die consisting of a grooved die that is continuously tapered to create a semicircular groove and a punch shaped like the die, and pressure is applied to the bending die by the rotation of the punch. Since the strip is gradually bent from both edges to the same radius as the tube to be formed, the following excellent effects can be obtained.

Since the number of processing times per unit time is greater than with a press, circular tubes can be formed from strips with high productivity.

Since the number of processing is large, the processing force per processing is small, so a compact forming machine is sufficient, and by applying it to forming high-tensile, thick-walled pipes and stainless steel pipes, it is efficient with inexpensive equipment. Can manufacture circular tubes.

Compared to the press method, the forming process is continuous, so
The welding torches can be easily tracked, forming and welding can be accurately continuous and automated, and it is possible to immediately move on to secondary processing such as pre-fitting, making it possible to convert final tubular products from strips with high productivity. can be obtained consistently and continuously.

[Brief explanation of drawings]

Figures 1 a to d are front views showing the forming principle of the circular tube forming method using a rotary swaging machine according to the present invention, Figure 2 is a side view showing the forming state, and Figure 3 is a plan view thereof. 4a and 4b are perspective views showing one example of the bending mold according to the present invention, FIG. 5 is a partially cutaway side view of the die in FIG. 4, FIG. 6 is a side view of the punch in FIG. 4, and FIG. Figures a and b are perspective views showing one example of a rotation stopper jig and a bending die to which it is attached in the present invention, Figure 8 is a perspective view showing how the same is arranged in a rotary swaging machine, and Figure 9 is Front view showing the relationship between the lid and the rotation stopper in pressurized and non-pressurized states, FIG. 10a,
b, c, d are perspective views showing the molding preparation stage, No. 11
The figure is a perspective view showing another embodiment of the bending mold used in the present invention, FIG. 12 is a sectional view showing the mold structure used in another embodiment of the present invention, and FIGS.
Fig. 14 is an explanatory diagram showing the pipe forming state according to the present invention, and Fig. 15 is a cross-sectional view showing the forming state step by step according to the embodiment shown in the figure. It is a graph showing the results of measuring diameter and wall thickness distribution. 1...Bending die, 2...Groove die, 3...Punch, 4...Rotary swaging machine, 5...
strip.

Claims (1)

[Claims] 1. An inlet groove composed of side curved surfaces for edge bending on both sides and a linear or curved bottom surface connecting these side curved surfaces, and this inlet groove becomes a semicircular groove on the outlet side. A bending mold consisting of a continuously tapered grooved die and a punch shaped like the grooved die is installed in a rotary swaging machine, and while sequentially feeding a predetermined length of the strip into the bending die, The bending die is held non-rotating at all times and a bending die is rotated around its outer periphery to apply pressure to the bending die, thereby gradually bending the strip from both edges at the same radius as the pipe. A circular tube forming method using a rotary swaging machine. 2. Using a rotary swaging machine according to claim 1, in which the bending die includes a finished part in which a semicircular groove of a required length is formed on the grooved die exit side and the punch exit side. Circular tube forming method. 3. It has an entrance groove composed of side curved surfaces for edge bending on both sides, a straight or curved shape connecting these side curved surfaces, and a bottom surface, and the entrance groove is continuously tapered so that it becomes a semicircular groove on the exit side. A bending die consisting of a groove-shaped die and a punch having a shape similar to the groove-shaped die is installed in a rotary saging machine, and while the strip is sequentially fed into the bending die for a predetermined length, the bending die is kept in a constant state of emergency. While the tape was held in rotation, a pressurizing force was applied to the bending mold by rotating a backer around its outer circumference, and the strip was bent gradually from both edges to the same radius as the tube, and then the circumference was divided into equal parts. A circular tube forming method using a rotary swaging machine, characterized in that a rotary bending die having a groove shape is rotated together with a backer to finish forming the entire circumference of the bending die into a circular shape. 4. A circular tube forming method using a rotary swaging machine according to claim 3, wherein a non-rotating bending die and a rotary bending die are arranged in series on the same rotary swaging machine. 5. A circular tube forming method using a rotary swaging machine according to claim 3, wherein a non-rotating bending die and a rotary bending die are placed in separate rotary swaging machines.