JPH0796332A - Method and device for burring tube - Google Patents

Abstract

PURPOSE:To facilitate the insertion of the forming head from the outer circumferential direction of a mother tube into the prepared hole to obtain the excellent workability, to execute the burring with a small forming head, and to uniformly arrange the height of the burring upper end surface. CONSTITUTION:The periphery of the prepared hole 2 of a mother tube 1 is pressed by two segmented outer dies 21. A forming head 20 is inserted from the outer circumferential side of the mother tube 1 (Arrow A). The forming head 20 is of segmented semi-piece shape. The forming head is moved to the direction of the arrow B until the conical surface 20a of the forming head 20 is brought into contact with the inner circumferential edge of the lower hole 2. The forming head 20 is turned as shown by the arrow D and drawn upward while being rotated so that the conical surface 20a may be brought into contact with the inner circumferential edge of the lower hole. The upper end surface of a burring part 4 is abutted on a stepped part 21 a of a burring guide hole 21b of the outer dies 21, and the height is uniformly arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burring process for forming a collar on a part of a wall of a mother pipe by forming a lower hole on the outer periphery of the mother pipe and then pulling it out while rotating a molding head inserted in the lower hole. The present invention relates to a method and an improvement of a burring machine used for implementing the method.

[0002]

2. Description of the Related Art A pilot hole is preliminarily formed in a pipe wall at a position where a collar of a mother pipe is to be formed, and the pilot hole is passed through by using a jig having a substantially conical side surface or a substantially hemispherical side surface. By forming a collar portion having a smaller diameter than the predetermined inner diameter of the collar to be molded, and then using the jig having the smaller diameter collar portion, at least a part of which has a length equal to the predetermined inner diameter of the collar. A burring process forming method for forming a collar portion having a predetermined inner diameter by passing a hole through the jig while rotating the jig is disclosed in JP-A-57-199252.
It is well known from Japanese Patent No.

In this burring method, there is no particular problem if the jig having a length equal to the predetermined inner diameter of the collar, which is used in the second step, has a shape that can be inserted from the longitudinal direction of the pipe. There is.

As a prior art, Japanese Patent Laid-Open No. 59-13530
The burring method disclosed in the publication is also well known. This processing method is a length that adds the amount of springback to the inner diameter of the mother tube,
Prepare a punch with a spheroid whose shorter diameter is shorter than the inner diameter of the mother tube, halved along the horizontal axis, and attach this punch to a ram equipped with a rotating mechanism via a chucking device. On the outside of the molding part, a die having a hole for color molding is fixed, the punch is inserted into the prepared hole of the mother tube from its long diameter side, and then withdrawn by the ram while rotating the punch in the mother tube, After inserting the punch, the edge of the pilot hole is deformed outward of the mother tube along the shape of the die.

In order to insert the punch into the mother tube, the major axis of the punch is aligned with the longitudinal direction of the mother tube, the part on one side from the axis of the punch is first inserted into the mother tube, and then the part on the opposite side is inserted. .

Further, as a third conventional technique, Japanese Patent Publication No. 3-2
The one disclosed in Japanese Patent No. 4286 is well known. In this burring method, the molding head 6 is inserted into the inside of the mother tube 1 as shown in FIG. 8B in the prepared hole 2 formed in the mother tube 1 of FIG. 8A.
The molding pin 5 is projected, and the molding head 6 is rotated upward as shown in FIG. After that, a molding jig 7 that spreads through the primary burring portion 3 in a direction perpendicular to the longitudinal direction of the pipe 1 is inserted into the pipe 1 as shown in FIG. Expand it and pull it out as shown in Fig. 8 (e) to perform non-rotating burring. 4 is a secondary burring processing part.

Reference numeral 8 denotes a molding head for performing non-rotating burring, and a molding jig 7 which is divided in half at the tip is attached by a not-shown intermediate cam provided in the head 8 so as to be expanded in the diameter direction. ing. Reference numeral 9 is a rod (shaft) to which the molding heads 6 and 8 are attached.

As shown in FIG. 9 (a), when a circular pilot hole 2 is formed in a cylindrical mother tube 1 and the collar, that is, a burring portion 4 is formed by burring with the above conventional technique, burring is performed. The height of the upper end surface 4a is not uniform all around ((b) of the same figure).

[0009]

In the first conventional technique, the jig used in the second step must be inserted from the longitudinal direction of the pipe, and cannot be inserted from the outer peripheral side of the mother pipe. There was a problem that was bad. Further, in the second conventional technique, in order to insert the punch into the pilot hole from the outer peripheral side of the mother tube, the major axis of the punch is aligned in the longitudinal direction of the mother tube, and first, a portion on one side from the axis of the punch is first inserted into the mother tube. It is necessary to insert and then insert the opposite part. Therefore, the punch shaft must be inserted while being tilted and swung, which is very troublesome and has a problem in that workability is poor as in the first prior art.

Furthermore, in the third prior art, the molding heads are complicated since the molding pins 6 and 8 are inserted from the outer circumference of the mother tube and then the molding pins are projected or the molding jig 7 is expanded. , Get bigger. Therefore, there is a problem in that the cost is high, the maintainability is deteriorated, the reliability is lowered, and the minimum burring diameter is limited due to the mechanism in the molding head, and the burring diameter cannot be reduced.

Therefore, a first object of the present invention is to provide a burring method for pipes which can solve these problems. Further, as described above, in the above-mentioned conventional technique, the height of the upper end surface 4a of the collar 4 formed by the burring process is not uniform, which is another problem.

Therefore, a second object of the present invention is to provide a burring method and a burring apparatus which can solve this problem.

[0013]

In order to achieve the first object, the burring method according to claim 1 is such that a base hole (2) is provided in the mother pipe (1) and the base hole (2) is provided in the base hole (2). In the burring processing method, in which the molding head (20) is inserted and then rotated while being pulled out, the molding head (20) is processed.
Is characterized in that it has a shape that is substantially halved on a plane parallel to the burring center axis (Z) and that it rotates or revolves around the burring center axis.

In order to achieve the second object, a burring method according to a second aspect is provided with a pilot hole (2) in the mother tube (1), and an outer die (21) is provided around the pilot hole (2). In the burring method in which the molding head (20) is inserted into the lower hole (2) and then pulled out while being rotated, the step portion () is formed on the inner surface of the burring guide hole (21b) in the outer die (21). 21a) is provided, and the upper end (4a) of the burring portion (4) is brought into contact with the step (21a) so that the upper end (4
It is characterized in that the heights of a) are made uniform.

A third aspect of the present invention is a burring apparatus used in the burring method for a pipe according to the second aspect, wherein the cross section of the burring guide hole (21b) perpendicular to the central axis is the mother tube (1). And an outer mold (21) having an elliptical shape with a major axis (φX) in the direction of the axis (XX).

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows an example of a molding head used for carrying out the present invention. A molding head 20 having a substantially halved shape is fixed to the lower end of a rod 19. It should be noted that the hatching in the same figure does not show a cross section, but is drawn to explain a portion where the molding head contacts the mother tube 1 during the burring process.

The hatched portion has a portion 20a of a conical surface and a portion 20b of a cylindrical surface. In FIG. 3, 1 is a mother tube, 2 is a lower hole, and 21 is an outer die that suppresses the periphery of the lower hole of the mother tube 1, and is composed of a split mold composed of two parts 21A and 21B. At this time, as shown in the figure, both parts 21A and 21B are fitted to the mother tube 1 and both parts are integrally fixed and used. The outer die 21, which is integrally fixed, is provided with a burring guide hole 21b having a step portion 21a at the upper portion and a molding head insertion hole 21c.

As shown in FIGS. 3A and 3B, the molding head 2
0 is inserted from above into the mother tube 2 from the outer peripheral direction of the mother tube through the forming head insertion hole 21c, the burring guide hole 21b and the lower hole 2 to perform burring.

As shown in FIG. 3 (a), the molding head 20 has a half-piece shape in which a plane parallel to Z passing through the vicinity of the burring center axis (center axis of the pilot hole 2) is halved. . Next, the steps of the burring method of the present invention will be described with reference to FIG.

First, as shown in FIG. 3A, the rod 19 is lowered as shown by the arrow A, as described in FIG.
The outer mold 21 is inserted into the pilot hole 2 from the outer periphery of the mother tube 1 whose pilot hole portion is suppressed.

Next, the rod 19 is moved to the right along the axis X-X of the mother tube 1 as shown by the arrow B so that the upper portion of the conical surface 20a contacts the inner circumference of the pilot hole 2. . here,
While turning the rod 19 to rotate the molding head 20,
It revolves along the inner peripheral edge of the pilot hole 2. At the same time, the molding head 20 is pulled upward as shown by arrow C. Then, as shown in FIG. 1B, the inner peripheral edge of the lower hole 2 of the mother tube 1 is burred upward (reference numeral 4).

Further, when the molding head 20 is pulled out and brought into the state shown in FIG. 3C, the maximum diameter portion (lower end portion in the drawing) of the molding head 20 expands the burring portion 4 and the outer mold 21.
It is pressed against the burring guide hole 21b, and the upper end surface of the burring is brought into contact with the step portion 21a, so that the height of the upper end surface is made uniform.

Then, the molding head 20 is pulled out upward and is also pulled out from the outer die 21. During burring,
As described above, the molding head 20 is pulled out while rotating / revolving while the hatched portion described in FIG. 2 is always in contact with the inner peripheral edge of the burring portion.

FIG. 1 (d) shows an orbit of revolution during burring by a dashed-dotted arrow D. The inner circumference of the burring guide hole 21b of the outer die 21 is, as shown in FIG.
Is an elliptical shape having a major axis φX in the direction of the axis line XX,
It has a minor axis φY in the YY direction, which is perpendicular to the X direction. φ is the inner diameter of the burring portion (color) 4 after burring, and the hatched portion in FIG. 4 shows the thickness of the burring portion (color) 4.

As shown in this figure, the wall thickness is large in the XX direction and small in the YY direction. Therefore, the closer to the Y-Y direction, the more the meat flow of the mother tube material during burring, and as a result, the height of the upper end surface 4a of the burring portion 4 becomes uniform over the entire circumference. This is shown in FIG. 5. The upward arrow in FIG. 5 is a comparative illustration of the degree of meat flow by the length of the arrow. FIG. 6 shows another embodiment. Compared with the embodiment of FIG. 4, the burring guide hole 21b ′ of the outer die 21 is provided.
However, it is not an ellipse but a perfect circle, and the diameter φA of the burring guide hole 21b ′ is shorter than the major diameter φX in the case of FIG. 4 and almost the same as the minor diameter φY (strictly slightly larger). Has been set. By doing so, the meat flow of the mother tube material during the burring process moves in the rotational direction as indicated by the arrow in FIG. 7. Then, the wall thickness of the burring portion becomes a value t smaller than that in the conventional technique. The height of the upper end surface 4a of the burring portion 4 is uniform over the entire circumference, as in the case of FIGS. 5 and 6.

[0026]

Since the present invention is constructed as described above, in the invention of claim 1, the molding head becomes small, so that it can be easily inserted from the outer peripheral side of the mother tube, and the workability is improved. The minimum burring diameter is not limited by the size of the molding head.

Further, according to the second aspect of the invention, even when the collar is formed by burring on the outer peripheral curved surface of the cylindrical tube or the like, the height of the upper end surface of the burring can be made uniform. Furthermore, in the invention of claim 3, it is possible to promote the uniformization of the height of the burring upper end surface.

[Brief description of drawings]

1 (a) to 1 (c) are cross-sectional views of a processed portion showing stepwise an embodiment of a burring method according to the present invention.
(A)-(c) is a figure of each stage, (d) is a top view explaining the revolution locus | trajectory of the molding head in the process stage.

FIG. 2 is a molding head used in the present invention, in which (a) is a plan view and (b) is a front view.

FIG. 3 is a view showing a state in which a mother tube used in the present invention, a molding head, and an outer die are combined, (a) is a vertical sectional front view, and (b) is a right side view.

FIG. 4 is a schematic plan view illustrating a horizontal cross section of an outer burring guide hole used in the present invention.

FIG. 5 is a front view showing an example of a mother tube processed by the processing method of the present invention.

FIG. 6 is a schematic plan view illustrating a horizontal cross section of a burring guide hole in another embodiment of the outer die used in the present invention.

FIG. 7 is a front view showing another example of the mother tube processed by the processing method of the present invention.

FIG. 8 is a diagram showing a conventional burring method step by step, and FIGS. 8A to 8E are sectional views showing the respective steps.

9A and 9B show a conventional mother tube shape, in which FIG. 9A is a front view before burring and FIG. 9B is a front view after burring.

[Explanation of symbols]

 1 Mother Tube 2 Lower Hole 4 Burring Processed Part (Color) 4a Upper End 20 Molding Head 21 Outer Mold 21a Steps 21b, 21b 'Burring Guide Hole XX Axis φX Long Diameter

Claims (3)

[Claims] 1. In a burring method in which a mother tube is provided with a pilot hole, and a molding head is inserted into the pilot hole and then pulled out while rotating, the molding head is substantially half-divided on a plane parallel to the burring center axis. A burring method for a pipe, which is characterized by having a curved shape and rotating or revolving around a burring central axis. 2. A burring method in which a mother pipe is provided with a pilot hole, the periphery of the pilot hole is restrained by an outer die, and a molding head is inserted into the pilot hole and then pulled out while being rotated, which is a burring inside the outer die. A method for burring a pipe, characterized in that a step portion is provided on the inner surface of the guide hole, and the upper end of the burring portion is brought into contact with the step portion so that the height of the upper end surface is made uniform. 3. The burring method according to claim 2, wherein the burring guide hole is provided with an outer die having a cross section perpendicular to the central axis of the burring guide hole and having an elliptical shape whose major axis is the axial direction of the mother tube. Burring machine used.