JPH02274328A - Manufacture of multistage bent and punched tube and punch used therefor - Google Patents

Abstract

PURPOSE:To easily punch a hole of a large inner diameter on a thick-wall tube by pressing a 1st punch from the upper surface of a bent tube to punch a hole of an oval section and notching both sides of the hole of an oval section with a 2nd punch in the shape of a circular arc to punch a circular hole. CONSTITUTION:When a 1st punching stage is carried out to hold the lower half of the tube 2, to press a 1st punch from the upper surface of the tube and to punch a hole of an oval section, slugs change into long and slender chips and fall in the tube. Further, when a 2nd punching stage is performed, arched slugs fall in the tube. Since the slugs punched in each stage are small, they are surely separated from the circumference of the hole and do not remain on the circumference of the hole. Since the respective slugs are long and slender, they are not stopped up or caught in the tube when they are flushed. In this way, a hole of a large inner diameter can be punched on the comparatively thick-wall tube and the slugs are not stopped up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a multi-bending perforated tube and a punch used therein. More specifically, the present invention relates to a method for manufacturing a somewhat thick-walled multi-stage bent tube, such as a tube for high-pressure piping, with holes somewhat smaller than its inner diameter, and a punch used therein.

[Prior Art] Conventionally, tubes for piping that are lightweight and require a small space, such as the piping for automobile air conditioners 1A2H, have been made using common piping fittings such as pulls, cheese, etc., as shown in Figure 6.
Unions, etc.) are not used as much as possible, and various processing (annular locking grooves (2D, bulge parts, etc.) are performed on the tube cap itself to allow it to play a part of the role of a connector.

Therefore, for example, a refrigerant charge valve adapter (23 in Figure 7) is fixed directly in the middle of the tube, and the tube has a relatively large diameter hole (6
There is a case where the holes (in the figure) are drilled.

When manufacturing such a multi-stage bent perforated tube, if the bending process is performed after the hole is drilled, the hole will become distorted (especially if the hole is located near the bend), making it impossible to insert an adapter or the like. Therefore, it is necessary to perform drilling after bending.

On the other hand, there are drilling and punching methods for perforation, but punching is usually preferable because it is faster, less likely to produce holes, and can easily form holes other than circular shapes. In particular, when inserting a charge valve adapter or the like into a machined hole and brazing the surrounding area, it is necessary to create a gap (5) between the periphery of the hole Q4 and the periphery of the hole Q4 for pouring the brazing material, as shown in Figure 8. In order to fix an adapter or the like while opening, it is preferable to form a hole with claw-like protrusions 4 at three locations.

However, with a tube that has been bent in advance, there is a problem in that punching chips tend to get stuck inside the tube. (As shown in Fig. 9, the bent portion of the tube is somewhat flattened during bending, so the scraps cannot escape to the outside, resulting in a defective product.

Therefore, conventionally, tubes with a simple shape (straight or one bend) and tube diameters of 14.5 ms or more (wall thickness 2.0 Dm) were punched, and multi-step bending (multiple bends) was performed. Complex shape, outer diameter 1
For tubes with a thickness of about 2 mm (wall thickness 1.75 to 2.00 mm) or less, multi-stage bent tubes are manufactured by drilling to produce fine chips.

[Problems to be Solved by the Invention] When drilling is performed using a drill, many burrs are generated on the inner and outer surfaces of the tube, and it is necessary to carry out a separate burr removal process.

Furthermore, drilling can only drill circular holes, making it impossible to form the claw-like protrusions 4 described above. Therefore, a hole is made that is somewhat smaller than the outer diameter of the adapter to be inserted, and the adapter is pushed into the hole to determine the mounting angle and temporarily fixed. However, in that case, there is no gap between the adapter and the inner edge of the hole, and the aluminum adapter thermally expands during the brazing process, so the brazing material may not flow into the gap and ultimately result in poor brazing. There is love.

The present invention solves the problems of the conventional manufacturing method, and provides a method for manufacturing a multi-stage bent perforated tube, which can easily produce a multi-stage bent perforated tube, and furthermore, can ensure the operation of brazing an adapter or the like. It is an object.

A further object of the present invention is to provide a punch that allows such a method to be easily carried out using conventional press machines and molds.

[Means for Solving the Problems] The method for manufacturing a multi-stage bent perforated tube of the present invention includes the steps of (a) bending a tube into a predetermined shape, and <b+holding the lower half of the bent tube. (c) a first punching step of punching a hole with an oval cross section by pressing the first punch from the upper surface of the tube; and a second punching step of cutting out an arcuate hole and drilling a substantially circular hole as a whole.

In such a method, it is preferable that the first punching step is performed with the longitudinal axis of the cross section of the first punch aligned with the longitudinal axis of the tube.

Furthermore, the punch of the present invention includes a second punch portion having a circular cross section;
a first punch part protruding from the tip of the second punch part for a length longer than the wall thickness of the tube to be processed, and the first punch part has a pair of circular arcs continuous with the surface of the second punch part. The periphery of the tip of the second punch section and the periphery of the tip of the first punch section are respectively cutting edges, and if necessary, a plurality of axially extending holes are provided on the surface of the second punch section. A book groove is formed.

[Operation] Hold the lower half of the tube and pull it from one side of the tube to the first
When a first punching step is performed in which a hole with an oval cross section is punched by pressing the punch, the scraps fall into elongated chips into the tube.

Further, when a second punching process is performed, arcuate scraps fall into the tube.

Since the scraps pulled out in each of the above steps are small, they are reliably separated from the periphery of the hole and do not remain stuck to the periphery of the hole. Moreover, each scrap is long and thin, so it won't get stuck or stuck inside the tube during flushing.

Furthermore, by aligning the longitudinal axis of the first punch with the longitudinal axis of the tube in the first punching step, each punched piece becomes almost flat, which has the advantage of ensuring that the layer falls into the tube and is less likely to get caught. There is.

[Example] Next, the molding method and punch of the present invention will be explained with reference to the drawings.

Fig. 1 is a sectional view showing the method of the present invention in the order of its steps;
The figure is a perspective view showing punching holes and scraps in each step shown in FIG. 1, FIG. 3 is a front view showing an embodiment of the punch of the present invention, and FIG. 4 is a bottom view of the punch shown in FIG. 3. Figure 5 is a cutaway front view of the end showing the mold incorporating the punch shown in Figure 3;
The figure is a perspective view showing an example of a tube manufactured by the method of the present invention, and FIG. 7 is a sectional view showing the tube of FIG. 5 with an adapter attached.

In Fig. 1, (0) is 4! where the pre-bent tube (2) is placed on the lower die (1). ! +1) indicates the first punching step, and (1) indicates the second punching step, and processing is performed in that order.

First, in the preparation step (0), the tube (2) is placed in the lower mold (
1). Since the tube (2) usually has a three-dimensional curved shape as shown in FIG. 6, it is preferable to use a positioning jig or the like to determine the position of the hole and the direction of extraction.

An upper mold (4) equipped with a punch (3) faces the tube (2). As shown in FIGS. 3 and 4, the punch (3) consists of a cylindrical second punch part (5) and a first punch part (6) which has a roughly oval cross section and projects from its tip. 1st
The height (11) of the punch part (6) is the same as the tube to be processed [2
It is preferable that the thickness be somewhat longer than that of No. 1, but it may be approximately the same.

The outer peripheral surface of the first punch part (6) is composed of a pair of cylindrical parts ('7) continuous from the second punch part (5) and a plane part (8) parallel to each other, As mentioned above, it has an oval-shaped cross section. The peripheral edges of the lower end surfaces of the first punch section (6) and the second punch section (5) each serve as a cutting edge. A conventionally known land portion or relief slope may be provided on each outer circumferential surface. Also, if necessary, 3
A punch with more than tiers may be used to divide the punched material into five or more parts.

In the extraction process in which the punch (3) is pressurized against the tube (2), as shown in Fig. 1, first the first punch part (6)
A first punching step (m) is performed in which the tube wall of the tube ('2J) is punched, and a hole ((9) in Fig. 2) corresponding to the cross-sectional shape of the first punch part (6) is formed, and an oval-shaped hole is formed. The scraps M fall into the tube (z).

Then, in the second punching step (1), the punch (3) is further pressurized against the tube (2), and the second punch portion (5) cuts out both sides of the hole (9) in an arcuate shape. As a result, as shown in FIG. 2, two arcuate scraps 01) fall into the tube (2), forming a circular hole 0z as a whole.

By drilling the hole in two steps as shown above, the cutout (G), 01) is divided into three small pieces, which remain on the periphery of the hole (7) and the tube (2). ) will not get caught inside.

If the direction of the first punch part (6) is aligned with the axis of the tube (2), the shape of each punched piece will be almost flat, which has the advantage of making it easier to pass through the inside of the -layer tube (z). .

In the method shown in FIGS. 1 and 2, the first and second steps are performed continuously using one punch (3), but in presses with small strokes, the two steps may be performed using separate punches.

Next, examples of molds and molded products used in the molding method shown in FIGS. 1 to 2 will be explained based on FIGS. 5 to 7.

Figure 5 shows a mold, in which a back plate supporting the punch (3) is slidably provided on the outer periphery of the punch (3) and is suspended from the back plate (toward) by a rod O11. Stripper plate G and a cylindrical elastic member (T) such as polyurethane rubber interposed between the two.
It consists of

The stripper plate is used to securely hold the tube (2) during processing, and to remove the tube (2) from the punch (3) using the elasticity of the elastic member after processing.

The method of the present invention can be applied to the middle of a multi-stage bent tube, for example, as shown in FIG.
It is particularly suitable for tubes with holes formed near the bent portion.

The material of the multi-stage bent perforated tube obtained by the method of the present invention is not particularly limited, and various tubes such as aluminum alloy, brass, and steel can be used.

Although there are no particular restrictions on the diameter and wall thickness of the tube, tubes with an outer diameter of 5 to 201@ and a thickness of about 0.5 to 5.0 ms are usually used. In addition, the inner diameter of the hole to be drilled suitable for the method of the present invention varies depending on the radius of curvature and the aspect ratio of the bending process, but is 40 to 90% of the inner diameter of the tube, preferably <60%.
It is about 70%.

The width of the punch hole (9) in the first step ((B) in FIG. 2) is preferably about 10 to 30% of the hole diameter (D). Width is 10%
If the diameter is smaller, the cross-sectional area of the first punch relative to the outer circumferential length (cutting length) will be smaller, so the strength of the punch tends to be insufficient.On the other hand, if it exceeds 30%, the amount of scraps will become large, so this is an advantage of using the method of the present invention. disappears.

V-shaped protrusion a on the periphery like tube (2) in Figure 2
If a force is to be generated, a V-groove OF3 extending in the axial direction may be formed on the outer periphery of the second punch portion (5) as shown in FIG. 3 and 4.

[Effects of the Invention] According to the method of the present invention, it is possible to easily drill a hole with a large inner diameter in a relatively thick tube, and since the scraps are divided into small pieces, there is no possibility of them clogging or getting caught inside the tube. There is nothing to do.

Fig. 1 is a sectional view showing the method of the present invention in the order of its steps;
The figure is a perspective view showing punching holes and scraps in each step shown in FIG. 1, FIG. 3 is a front view showing an embodiment of the punch of the present invention, and FIG. 4 is a bottom view of the punch shown in FIG. 3. Figure 5 is a partially cutaway front view showing the mold incorporating the punch shown in Figure 3;
Figure 7 is a perspective view showing an example of a tube formed by the method of the present invention, Figure 7 is a sectional view showing the tube in Figure 5 with a valve attached, and Figure 8 is an example of holes in a conventional tube. The plan view shown in FIG. 9 is a sectional view showing an example of a conventional tube.

(Main symbols on drawings) (2), ■: Tube (3): Punch (5): Second punch part (6): 1st punch part (9), 02J: Hole η, old): scraps

[Brief explanation of drawings]

talent 1 figure age 3 figure 2nd time 5th figure Figure 6 8 years old

Claims (1)

[Claims] 1. (a) A step of bending the tube into a predetermined shape, (b) A step of holding the lower half of the bent tube at the perforation site, and (c) A step of bending the tube from the top surface of the tube. a first punching step of punching a hole with an oval cross section by pressing a first punch; (d) notching each side of the hole with an oval cross section at least once in an arc shape with a second punch; A method for manufacturing a multi-stage bent perforated tube comprising a second punching step of punching circular holes. 2. The manufacturing method according to claim 1, wherein the first punching step is performed by aligning the longitudinal axis of the cross section of the first punch with the longitudinal axis of the tube. 3 It has a second punch part with a circular cross section, and a first punch part that protrudes longer than the wall thickness of the tube to be processed from the tip of the second punch part, and the first punch part is connected to the second punch part. Used in the method according to claim 1, wherein the punch has an oval-shaped cross section with a pair of circular arcs continuous with the surface of the punch, and the tip periphery of the second punch portion and the tip periphery of the first punch portion each serve as a cutting edge. Punch. 4. The punch according to claim 3, wherein a plurality of grooves extending in the axial direction are formed on the surface of the second punch portion.